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Changelog

This project follows Semantic Versioning. Due to the nature of Biome as a toolchain, it can be unclear what changes are considered major, minor, or patch. Read our guidelines to categorize a change.

New entries must be placed in a section entitled Unreleased. Read our guidelines for writing a good changelog entry.

  • Add partial for .astro files. Biome is able to sort imports inside the frontmatter of the Astro files. Contributed by @ematipico

    ---
    import { getLocale } from "astro:i18n";
    import { Code } from "astro:components";
    import { getLocale } from "astro:i18n";
    import { Code } from "astro:components";
    ---
    <div></div>
  • Add partial for .vue files. Biome is able to sort imports inside the script block of Vue files. Contributed by @nhedger

    <script setup lang="ts">
    - import Button from "./components/Button.vue";
    - import * as vueUse from "vue-use";
    + import * as vueUse from "vue-use";
    + import Button from "./components/Button.vue";
    </script/>
    <template></template>
  • Add partial for .svelte files. Biome is able to sort imports inside the script block of Svelte files. Contributed by @ematipico

    <script setup lang="ts">
    - import Button from "./components/Button.svelte";
    - import * as svelteUse from "svelte-use";
    + import * as svelteUse from "svelte-use";
    + import Button from "./components/Button.svelte";
    </script/>
    <div></div>
  • noUnusedVariables ignores unused rest spread silbings.

    The following code is now valid:

    const { a, ...rest } = { a: 0, b: 1 };
    console.log(rest);

    Contributed by @ah-yu

  • Fix #1748. Now for the following case we won’t provide an unsafe fix for the noNonNullAssertion rule:

  • Imports that contain the protocol : are now sorted after the npm: modules, and before the URL modules. Contributed by @ematipico

    import express from "npm:express";
    import Component from "./component.js"
    import { sortBy } from "virtual:utils";
    import { sortBy } from "virtual:utils";
    import Component from "./component.js"
    x[y.z!];

    Contributed by @ah-yu

  • Fix #1081. The useAwait rule does not report for await...of. Contributed by @unvalley

  • Fix #1827 by properly analyzing nested try-finally statements. Contributed by @ah-yu

  • Add a new command biome migrate prettier. The command will read the file .prettierrc/prettier.json and .prettierignore and map its configuration to Biome’s one. Due to the different nature of .prettierignore globs and Biome’s globs, it’s highly advised to make sure that those still work under Biome.

  • Now the file name printed in the diagnostics is clickable. If you run the CLI from your editor, you can Ctrl/ + Click on the file name, and the editor will open said file. If row and columns are specified e.g. file.js:32:7, the editor will set the cursor right in that position. Contributed by @ematipico

  • Add an option --linter to biome rage. The option needs to check Biome linter configuration. Contributed by @seitarof

  • Add an option --formatter to biome rage. The option needs to check Biome formatter configuration. Contributed by @seitarof

  • The CLI now consistently reports the number of files tha were changed, out of the total files that were analysed. Contributed by @ematipico

  • The CLI now consistently shows the number of errors and warnings emitted. Contributed by @ematipico

  • Don’t process files under an ignored directory.

    Previously, Biome processed all files in the traversed hierarchy, even the files under an ignored directory. Now, it completly skip the content of ignored directories.

  • Fix #1508 by excluding deleted files from being processed. Contributed by @ematipico

  • Fix #1173. Fix the formatting of a single instruction with commented in a control flow body to ensure consistency. Contributed by @mdm317

  • Fix overriding of javascript.globals. Contributed by @arendjr

  • Fix a bug where syntax rules weren’t run when pulling the diagnostics. Now Biome will emit more parsing diagnostics, e.g.

    check.js:1:17 parse/noDuplicatePrivateClassMembers ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    × Duplicate private class member "#foo"
    > 1 │ class A { #foo; #foo }
    │ ^^^^

    Contributed by @ematipico

  • Removed a superfluous diagnostic that was printed during the linting/check phase of a file:

    test.js check ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    × The file contains diagnostics that needs to be addressed.

    Contributed by @ematipico

  • Add the ability to resolve the configuration files defined inside extends from the node_modules/ directory.

    If you want to resolve a configuration file that matches the specifier @org/configs/biome, then your package.json file must look this:

    {
    "name": "@org/configs",
    "exports": {
    "./biome": "./biome.json"
    }
    }

    And the biome.json file that “imports” said configuration, will look like this:

    {
    "extends": "@org/configs/biome"
    }

    Read the documentation to better understand how it works, expectations and restrictions.

  • Fix a regression where ignored files where formatted in the editor. Contributed by @ematipico
  • Fix a bug where syntax rules weren’t run when pulling the diagnostics. Now Biome will emit more parsing diagnostics, e.g.
    check.js:1:17 parse/noDuplicatePrivateClassMembers ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
    × Duplicate private class member "#foo"
    > 1 │ class A { #foo; #foo }
    │ ^^^^
    Contributed by @ematipico
  • Biome now allows to format the package.json file. This is now the default behaviour and users can remove their workarounds. If you rely on other tools to format package.json, you’ll have to ignore it via configuration. Contributed by @pattrickrice

  • New formatter option attributePosition that have similar behavior as Prettier singleAttributePerLine #1706. Contributed by @octoshikari

  • Add partial for .astro files. Biome is able to format the frontmatter of the Astro files. Contributed by @ematipico

    ---
    statement ( );
    statement();
    ---
    <div></div>
  • Add partial for .vue files. Biome is able to format the script block of Vue files. Contributed by @nhedger

    <script setup lang="ts">
    statement ( );
    statement();
    </script/>
    <template></template>
  • Add partial for .svelte files. Biome is able to format the script block of Svelte files. Contributed by @ematipico

    <script setup lang="ts">
    statement ( );
    statement();
    </script/>
    <div></div>
  • composer.json, deno.json, jsconfig.json, package.json and tsconfig.json are no longer protected files.

    This means that you can now format them.

    If you want to ignore these files, you can use the files.ignore configuration:

    {
    "files": {
    "ignore": [
    "composer.json",
    "jsconfig.json",
    "package.json",
    "tsconfig.json",
    "typescript.json",
    "deno.json",
    "deno.jsonc"
    ]
    }
    }

    The following files are still protected, and thus ignored:

    • composer.lock
    • npm-shrinkwrap.json
    • package-lock.json
    • yarn.lock

    Contributed by @pattrickrice and @Conaclos

  • Fix #1039. Check unicode width instead of number of bytes when checking if regex expression is a simple argument.

    This no longer breaks.

    s(/🚀🚀/).s().s();

    Contributed by @kalleep

  • Fix #1218, by correctly preserving empty lines in member chains. Contributed by @ah-yu

  • Add the rule noSkippedTests, to disallow skipped tests:

    describe.skip("test", () => {});
    it.skip("test", () => {});

    Contributed by @ematipico

  • Add the rule noFocusedTests, to disallow skipped tests:

    describe.only("test", () => {});
    it.only("test", () => {});

    Contributed by @ematipico

  • Add rule useSortedClasses, to sort CSS utility classes:

    <div class="px-2 foo p-4 bar" />
    <div class="foo·bar·p-4·px-2" />

    Contributed by @DaniGuardiola

  • Add rule noUndeclaredependencies, to detect the use of dependencies that aren’t present in the package.json

  • Add rule noNamespaceImport, to report namespace imports:

    import * as foo from "foo";

    Contributed by @unvalley

  • Add partial support for .astro files. Biome is able to lint and fix the frontmatter of the Astro files. Contributed by @ematipico

    ---
    delete a.b
    a.b = undefined
    ---
    <div></div>
  • Add partial support for .vue files. Biome is able to lint and fix the script block of the Vue files. Contributed by @nhedger

    <script setup lang="ts">
    delete a.b
    a.b = undefined
    <script>
    <template></template>
  • Add rule useNodeAssertStrict, which promotes the use of node:assert/strict over node:assert. Contributed by @ematipico

  • Add rule noExportsInTest which disallows export or modules.exports in files containing test. Contributed by @ah-yu

  • Add rule noSemicolonInJsx to detect possible wrong semicolons inside JSX elements.

    const Component = () => {
    return (
    <div>
    <div />;
    </div>
    );
    }

    Contributed by @fujiyamaorange

  • noUselessTernary now provides unsafe code fixes. Contributed by @vasucp1207

  • noApproximativeNumericConstant now provides unsafe code fixes and handle numbers without leading zero and numbers with digit separators.

    The following numbers are now reported as approximated constants.

    3.14_15; // PI
    .4342; // LOG10E

    Contributed by @Conaclos

  • noPrecisionLoss no longer reports number with extra zeros.

    The following numbers are now valid.

    .1230000000000000000000000;
    1230000000000000000000000.0;

    Contributed by @Conaclos

  • useNamingConvention now supports unicase letters (#1786).

    unicase letters have a single case: they are neither uppercase nor lowercase. Previously, Biome reported names in unicase as invalid. It now accepts a name in unicase everywhere.

    The following code is now accepted:

    const 안녕하세요 = { 안녕하세요: 0 };

    We still reject a name that mixes unicase characters with lowercase or uppercase characters: The following names are rejected:

    const A안녕하세요 = { a안녕하세요: 0 };

    Contributed by @Conaclos

  • useNamingConvention and useFilenamingConvention now provides a new option requireAscii to require identifiers to be in ASCII.

    To avoid any breaking change, this option is turned off by default. We intend to turn it on in the next major release of Biome (Biome 2.0).

    Set the requireAscii rule option to true to require identifiers to be in ASCII.

    {
    "linter": {
    "rules": {
    "style": {
    "useNamingConvention": { "options": { "requireAscii": false } }
    },
    "nursery": {
    "useFilenamingConvention": { "options": { "requireAscii": false } }
    }
    }
    }
    }

    Contributed by @Conaclos

  • Fix missing link in noStaticOnlyClass documentation. Contributed by @yndajas

  • noConfusingVoidType no longer reports valid use of the void type in conditional types (#1812).

    The rule no longer reports the following code:

    type Conditional<T> = T extends void ? Record<string, never> : T

    Contributed by @lucasweng

  • noInvalidUseBeforeDeclaration no longer reports valid use of binding patterns (#1648).

    The rule no longer reports the following code:

    const { a = 0, b = a } = {};

    Contributed by @Conaclos

  • noUnusedVariables no longer reports used binding patterns (#1652).

    The rule no longer reports a as unused the following code:

    const { a = 0, b = a } = {};
    export { b };

    Contributed by @Conaclos

  • Fix #1651. noVar now ignores TsGlobalDeclaration. Contributed by @vasucp1207

  • Fix #1640. useEnumInitializers code action now generates valid code when last member has a comment but no comma. Contributed by @kalleep

  • Fix #1653. Handle a shorthand value in useForOf to avoid the false-positive case. Contributed by @togami2864

  • Fix #1656. useOptionalChain code action now correctly handles logical and chains where methods with the same name are invoked with different arguments:

    tags·&&·tags.includes('a')·&&·tags.includes('b')
    tags?.includes('a') && tags.includes('b')

    Contributed by @lucasweng

  • Fix #1704. Convert / to escaped slash \/ to avoid parsing error in the result of autofix. Contributed by @togami2864

  • Fix#1697. Preserve leading trivia in autofix of suppression rules. Contributed by @togami2864

  • Fix #603. Trim trailing whitespace to avoid double insertion. Contributed by @togami2864

  • Fix #1765. Now the rule noDelete doesn’t trigger when deleting a dataset:

    delete element.dataset.prop;

    Contributed by @ematipico

  • useNamingConvention and useFilenamingConvention now reject identifiers with consecutive delimiters.

    The following name is now invalid because it includes two underscores:

    export const MY__CONSTANT = 0;

    Note that we still allow consecutive leading and consecutive trailing underscores.

    Contributed by @Conaclos

  • Fix #1728. Correctly parse the global declaration when the { token is on the line following the global keyword.

    Now the following code is correctly parsed:

    declare global
    { }
    declare module foo {
    global
    { }
    }

    Contributed by @ah-yu

  • Fix #1730. Correctly parse delete expressions with operands that are not simple member expressions.

    delete(a.b);
    delete console.log(1);
    delete(() => {});

    Contributed by @printfn

  • Fix #1584. Ensure the LSP only registers the formatter once. Contributed by @nhedger

  • Fix #1589. Fix invalid formatting of own line comments when they were at the end of an import/export list. Contributed by @spanishpear

  • Override correctly the recommended preset (#1349).

    Previously, if unspecified, Biome turned on the recommended preset in overrides. This resulted in reporting diagnostics with a severity level set to off. This in turn caused Biome to fail.

    Now Biome won’t switch on the recommended preset in overrides unless told to do so.

    Contributed by @Conaclos

  • Don’t format ignored files that are well-known JSONC files when files.ignoreUnknown is enabled (#1607).

    Previously, Biome always formatted files that are known to be JSONC files (e.g. .eslintrc) when files.ignoreUnknown was enabled.

    Contributed by @Conaclos

  • Fix #1178, where the line ending option wasn’t correctly applied. Contributed by @ematipico
  • Fix #1571. Fix invalid formatting of nested multiline comments. Contributed by @ah-yu

Fix #1575. noArrayIndexKey now captures array index value inside template literals and with string concatination. Contributed by @vasucp1207

  • Accept the const modifier for type parameter in method type signature (#1624).

    The following code is now correctly parsed:

    type Foo = {
    <const T>();
    method<const T>();
    };

    Contributed by @magic-akari

  • Correctly parse type arguments in expression(#1184).

    The following code is now correctly parsed in typescript:

    0 < (0 >= 1);

    Contributed by @ah-yu

  • Generate Open Graph images based on the linked page. Contributed by @ematipico

  • Fix examples of the git hook page. Contributed by @9renpoto, @lmauromb, and @Conaclos

  • Fix dead and erroneous hyperlinks. Contributed by @Sec-ant and Conaclos

  • Fix #1512 by skipping verbose diagnostics from the count. Contributed by @ematipico

  • Correctly handle cascading include and ignore.

    Previously Biome incorrectly included files that were included at tool level and ignored at global level. In the following example, file.js was formatted when it should have been ignored. Now, Biome correctly ignores the directory ./src/sub/.

    Terminal window
    tree src
    src
    └── sub
    └── file.js
    cat biome.json
    {
    "files": { "ignore": ["./src/sub/"] },
    "formatter": { "include": ["./src"] }
    }

    Contributed by @Conaclos

  • Don’t emit verbose warnings when a protected file is ignored.

    Some files, such as package.json and tsconfig.json, are protected. Biome emits a verbose warning when it encounters a protected file.

    Previously, Biome emitted this verbose warning even if the file was ignored by the configuration. Now, it doesn’t emit verbose warnings for protected files that are ignored.

    Contributed by @Conaclos

  • overrides no longer affect which files are ignored. Contributed by @Conaclos

  • The file biome.json can’t be ignored anymore. Contributed by @ematipico

  • Fix #1541 where the content of protected files wasn’t returned to stdout. Contributed by @ematipico

  • Don’t handle CSS files, the formatter isn’t ready yet. Contributed by @ematipico

  • Fix 1440, a case where extends and overrides weren’t correctly emitting the final configuration. Contributed by @arendjr

  • Correctly handle include when ignore is set (#1468). Contributed by @Conaclos

    Previously, Biome ignored include if ignore was set. Now, Biome check both include and ignore. A file is processed if it is included and not ignored. If include is not set all files are considered included.

  • Fix placement of comments before * token in generator methods with decorators. #1537 Contributed by @ah-yu

  • Fix #1406. Ensure comments before the async keyword are placed before it. Contributed by @ah-yu

  • Fix #1172. Fix placement of line comment after function expression parentheses, they are now attached to first statement in body. Contributed by @kalleep

  • Fix #1511 that made the JavaScript formatter crash. Contributed @Conaclos

  • Add an unsafe code fix for noConsoleLog. Contributed by @vasucp1207

  • useArrowFunction no longer reports function in extends clauses or in a new expression. Contributed by @Conaclos

    These cases require the presence of a prototype.

  • Add dependency variable names on error message when useExhaustiveDependencies rule shows errors. Contributed by @mehm8128

  • The fix of useArrowFunction now adds parentheses around the arrow function in more cases where it is needed (#1524).

    A function expression doesn’t need parentheses in most expressions where it can appear. This is not the case with the arrow function. We previously added parentheses when the function appears in a call or member expression. We now add parentheses in binary-like expressions and other cases where they are needed, hopefully covering all cases.

    Previously:

    f = f ?? function() {};
    f = f ?? () => {};

    Now:

    f = f ?? function() {};
    f = f ?? (() => {});

    Contributed by @Conaclos

  • Fix #1514. Fix autofix suggestion to avoid the syntax error in no_useless_fragments. Contributed by @togami2864

  • The diagnostics files/missingHandler are now shown only when the option --verbose is passed. Contributed by @ematipico
  • The diagnostics for protected files are now shown only when the option --verbose is passed. Contributed by @ematipico
  • Fix #1465, by taking in consideration the workspace folder when matching a pattern. Contributed by @ematipico
  • Fix #1465, by correctly process globs that contain file names. Contributed by @ematipico
  • Fix #1170. Fix placement of comments inside default switch clause. Now all line comments that have a preceding node will keep their position. Contributed by @kalleep

Fix #1335. noUselessFragments now ignores code action on component props when the fragment is empty. Contributed by @vasucp1207

  • useConsistentArrayType was accidentally placed in the style rule group instead of the nursery group. It is now correctly placed under nursery.

Fix #1483. useConsistentArrayType now correctly handles its option. Contributed by @Conaclos

Fix #1502. useArrowFunction now correctly handle functions that return a (comma) sequence expression. Contributed by @Conaclos

Previously the rule made an erroneous suggestion:

f(function() { return 0, 1; }, "");
f(() => 0, 1, "")

Now, the rule wraps any comma sequence between parentheses:

f(function() { return 0, 1; }, "");
f(() => (0, 1), "")

Fix #1473: useHookAtTopLevel now correctly handles React components and hooks that are nested inside other functions. Contributed by @arendjr

Biome now scores 97% compatibility with Prettier and features more than 180 linter rules.

  • Biome now shows a diagnostic when it encounters a protected file. Contributed by @ematipico

  • The command biome migrate now updates the $schema if there’s an outdated version.

  • The CLI now takes in consideration the .gitignore in the home directory of the user, if it exists. Contributed by @ematipico

  • The biome ci command is now able to print GitHub Workflow Commands when there are diagnostics in our code. Contributed by @nikeee This might require setting the proper permissions on your GitHub action:

    permissions:
    pull-requests: write
  • The commands format, lint, check and ci now accept two new arguments: --changed and --since. Use these options with the VCS integration is enabled to process only the files that were changed. Contributed by @simonxabris

    Terminal window
    biome format --write --changed
  • Introduced a new command called biome explain, which has the capability to display documentation for lint rules. Contributed by @kalleep

  • You can use the command biome explain to print the documentation of lint rules. Contributed by @kalleep

    Terminal window
    biome explain noDebugger
    biome explain useAltText
  • You can use the command biome explain to print the directory where daemon logs are stored. Contributed by @ematipico

    Terminal window
    biome explain daemon-logs
  • Removed the hard coded limit of 200 printable diagnostics. Contributed by @ematipico

  • Fix #1247, Biome now prints a warning diagnostic if it encounters files that can’t handle. Contributed by @ematipico

    You can ignore unknown file types using the files.ignoreUnknown configuration in biome.json:

    {
    "files": {
    "ignoreUnknown": true
    }
    }

    Or the --files-ignore-unknown CLI option:

    Terminal window
    biome format --files-ignore-unknown=true --write .
  • Fix #709 and #805 by correctly parsing .gitignore files. Contributed by @ematipico

  • Fix #1117 by correctly respecting the matching. Contributed by @ematipico

  • Fix #691 and #1190, by correctly apply the configuration when computing overrides configuration. Contributed by @ematipico

  • Users can specify git ignore patterns inside ignore and include properties, for example it’s possible to allow list globs of files using the ! character:

    {
    "files": {
    "ignore": [
    "node_modules/**",
    "!**/dist/**" // this is now accepted and allow files inside the `dist` folder
    ]
    }
    }
  • The LSP registers formatting without the need of using dynamic capabilities from the client.

    This brings formatting services to the editors that don’t support or have limited support for dynamic capabilities.

  • Fix #1169. Account for escaped strings when computing layout for assignments. Contributed by @kalleep

  • Fix #851. Allow regular function expressions to group and break as call arguments, just like arrow function expressions. #1003 Contributed by @faultyserver

  • Fix #914. Only parenthesize type-casted function expressions as default exports. #1023 Contributed by @faultyserver

  • Fix #1112. Break block bodies in case clauses onto their own lines and preserve trailing fallthrough comments. #1035 Contributed by @faultyserver

  • Fix RemoveSoftLinesBuffer behavior to also removed conditional expanded content, ensuring no accidental, unused line breaks are included #1032 Contributed by @faultyserver

  • Fix #1024. Allow JSX expressions to nestle in arrow chains #1033 Contributed by @faultyserver

  • Fix incorrect breaking on the left side of assignments by always using fluid assignment. #1021 Contributed by @faultyserver

  • Fix breaking strategy for nested object patterns in function parameters #1054 Contributed by @faultyserver

  • Fix over-indention of arrow chain expressions by simplifying the way each chain is grouped #1036, #1136, and #1162 Contributed by @faultyserver.

  • Fix “simple” checks for calls and member expressions to correctly handle array accesses, complex arguments to single-argument function calls, and multiple-argument function calls. #1057 Contributed by @faultyserver

  • Fix text wrapping and empty line handling for JSX Text elements to match Prettier’s behavior. #1075 Contributed by @faultyserver

  • Fix leading comments in concisely-printed arrays to prevent unwanted line breaks. #1135 Contributed by @faultyserver

  • Fix best_fitting and interned elements preventing expansion propagation from sibling elements. #1141 Contributed by @faultyserver

  • Fix heuristic for grouping function parameters when type parameters with constraints are present. #1153. Contributed by @faultyserver.

  • Fix binary-ish and type annotation handling for grouping call arguments in function expressions and call signatures. #1152 and #1160 Contributed by @faultyserver

  • Fix handling of nestled JSDoc comments to preserve behavior for overloads. #1195 Contributed by @faultyserver

  • Fix #1208. Fix extraction of inner types when checking for simple type annotations in call arguments. #1195 Contributed by @faultyserver

  • Fix #1220. Avoid duplicating comments in type unions for mapped, empty object, and empty tuple types. #1240 Contributed by @faultyserver

  • Fix #1356. Ensure if_group_fits_on_line content is always written in RemoveSoftLinesBuffers. #1357 Contributed by @faultyserver

  • Fix #1171. Correctly format empty statement with comment inside arrow body when used as single argument in call expression. Contributed by @kalleep

  • Fix #1106. Fix invalid formatting of single bindings when Arrow Parentheses is set to “AsNeeded” and the expression breaks over multiple lines. #1449 Contributed by @faultyserver

New rules are incubated in the nursery group. Once stable, we promote them to a stable group. The following rules are promoted:

  • Add useExportType that enforces the use of type-only exports for types. Contributed by @Conaclos

    interface A {}
    interface B {}
    class C {}
    export type { A, C }
    export { type A, C }
    export { type B }
    export type { B }
  • Add useImportType that enforces the use of type-only imports for types. Contributed by @Conaclos

    import { A, B } from "./mod.js";
    import { type A, B } from "mod";
    let a: A;
    const b: B = new B();

    Also, the rule groups type-only imports:

    import { type A, type B } from "./mod.js";
    import type { A, B } from "./mod.js";
  • Add useFilenamingConvention, that enforces naming conventions for JavaScript and TypeScript filenames. Contributed by @Conaclos

    By default, the rule requires that a filename be in camelCase, kebab-case, snake_case, or matches the name of an export in the file. The rule provides options to restrict the allowed cases.

  • Add useNodejsImportProtocol that enforces the use of the node: protocol when importing Node.js modules. Contributed by @2-NOW, @vasucp1207, and @Conaclos

    import fs from "fs";
    import fs from "node:fs";
  • Add useNumberNamespace that enforces the use of the Number properties instead of the global ones.

    parseInt;
    Number.parseInt;
    - Infinity;
    Number.NEGATIVE_INFINITY;
  • Add useShorthandFunctionType that enforces using function types instead of object type with call signatures. Contributed by @emab, @ImBIOS, and @seitarof

    interface Example {
    (): string;
    }
    type Example = () => string
- Add [noNodejsModules](https://biomejs.dev/linter/rules/no-nodejs-modules), that disallows the use of _Node.js_ modules. Contributed by @anonrig, @ematipico, and @Conaclos
- Add [noInvalidUseBeforeDeclaration](https://biomejs.dev/linter/rules/no-invalid-use-before-declaration) that reports variables and function parameters used before their declaration. Contributed by @Conaclos
```js
function f() {
console.log(c); // Use of `c` before its declaration.
const c = 0;
}
  • Add useConsistentArrayType that enforces the use of a consistent syntax for array types. Contributed by @eryue0220

    This rule will replace useShorthandArrayType. It provides an option to choose between the shorthand or the generic syntax.

  • Add noEmptyTypeParameters that ensures that any type parameter list has at least one type parameter. Contributed by @togami2864

    This will report the following empty type parameter lists:

    interface Foo<> {}
    // ^^
    type Bar<> = {};
    // ^^
  • Add noGlobalEval that reports any use of the global eval. Contributed by @you-5805

  • Add noGlobalAssign that reports assignment to global variables. Contributed by @chansuke

    Object = {}; // report assignment to `Object`.
  • Add noMisleadingCharacterClass that disallows characters made with multiple code points in character class. Contributed by @togami2864

  • Add noThenProperty that disallows the use of then as property name. Adding a then property makes an object thenable that can lead to errors with Promises. Contributed by @togami2864

  • Add noUselessTernary that disallows conditional expressions ( ternaries) when simpler alternatives exist.

    var a = x ? true : true; // this could be simplified to `x`

Fix #1061. noRedeclare no longer reports overloads of export default function. Contributed by @Conaclos

The following code is no longer reported:

export default function(a: boolean): boolean;
export default function(a: number): number;
export default function(a: number | boolean): number | boolean {
return a;
}

Fix #651, useExhaustiveDependencies no longer reports out of scope dependencies. Contributed by @kalleep

The following code is no longer reported:

let outer = false;
const Component = ({}) => {
useEffect(() => {
outer = true;
}, []);
}

Fix #1191. noUselessElse now preserve comments of the else clause. Contributed by @Conaclos

For example, the rule suggested the following fix:

function f(x) {
if (x <0) {
return 0;
}
// Comment
else {
return x;
}
}

Now the rule suggests a fix that preserves the comment of the else clause:

function f(x) {
if (x <0) {
return 0;
}
// Comment
else {
return x;
}
}

Fix #1383. noConfusingVoidType now accepts the void type in type parameter lists.

The rule no longer reports the following code:

f<void>();

Fix #728. useSingleVarDeclarator no longer outputs invalid code. Contributed by @Conaclos

Fix #1167. useValidAriaProps no longer reports aria-atomic as invalid. Contributed by @unvalley

Fix #1192. useTemplate now correctly handles parenthesized expressions and respects type coercions. Contributed by @n-gude

These cases are now properly handled:

"a" + (1 + 2) // `a${1 + 2}`
1 + (2 + "a") // `${1}${2}a`

Fix #1456. useTemplate now reports expressions with an interpolated template literal and non-string expressions. Contributed by @n-gude

The following code is now reported:

`a${1}` + 2;

Fix #1436. useArrowFunction now applies a correct fix when a function expression is used in a call expression or a member access. Contributed by @Conaclos

For example, the rule proposed the following fix:

const called = function() {}();
const called = () => {}();

It now proposes a fix that adds the needed parentheses:

const called = function() {}();
const called = (() => {})();

Fix #696. useHookAtTopLevel now correctly detects early returns before the calls to the hook.

  • The code fix of noUselessTypeCOnstraint now adds a trailing comma when needed to disambiguate a type parameter list from a JSX element. COntributed by @Conaclos

Fix #578. useExhaustiveDependencies now correctly recognizes hooks namespaced under the React namespace. Contributed by @XiNiHa

Fix #910. noSvgWithoutTitle now ignores <svg> element with aria-hidden="true". COntributed by @vasucp1207

  • The representation of imports has been simplified. Contributed by @Conaclos

    The new representation is closer to the ECMAScript standard. It provides a single way of representing a namespace import such as import * as ns from "". It rules out some invalid states that was previously representable. For example, it is no longer possible to represent a combined import with a type qualifier such as import type D, { N } from "".

    See #1163 for more details.

  • Imports and exports with both an import attribute and a type qualifier are now reported as parse errors.

    import type A from "mod" with { type: "json" };
    // ^^^^ ^^^^^^^^^^^^^^^^^^^^^
    // parse error
  • Fix #1077 where parenthesized identifiers in conditional expression were being parsed as arrow expressions. Contributed by @kalleep

    These cases are now properly parsed:

    JavaScript:

    a ? (b) : a => {};

    TypeScript:

    a ? (b) : a => {};

    JSX:

    bar ? (foo) : (<a>{() => {}}</a>);
  • Allow empty type parameter lists for interfaces and type aliases (#1237). COntributed by @togami2864

    TypeScript allows interface declarations and type aliases to have empty type parameter lists. Previously Biome didn’t handle this edge case. Now, it correctly parses this syntax:

    interface Foo<> {}
    type Bar<> = {};
  • Rename the biome_js_unicode_table crate to biome_unicode_table (#1302). COntributed by @chansuke
  • Fix #933. Some files are properly ignored in the LSP too. E.g. package.json, tsconfig.json, etc.
  • Fix #1394, by inferring the language extension from the internal saved files. Now newly created files JavaScript correctly show diagnostics.
  • Fix some accidental line breaks when printing array expressions within arrow functions and other long lines #917. Contributed by @faultyserver

  • Match Prettier’s breaking strategy for ArrowChain layouts #934. Contributed by @faultyserver

  • Fix double-printing of leading comments in arrow chain expressions #951. Contributed by @faultyserver

  • Fix #910, where the rule noSvgWithoutTitle should skip elements that have aria-hidden attributes. Contributed by @vasucp1207
  • Add useForOf rule. The rule recommends a for-of loop when the loop index is only used to read from an array that is being iterated. Contributed by @victor-teles
  • Address #924 and #920. noUselessElse now ignores else clauses that follow at least one if statement that doesn’t break early. Contributed by @Conaclos

    For example, the following code is no longer reported by the rule:

    function f(x) {
    if (x < 0) {
    // this `if` doesn't break early.
    } else if (x > 0) {
    return x;
    } else {
    // This `else` block was previously reported as useless.
    }
    }

Fix #918. useSimpleNumberKeys no longer repports false positive on comments. Contributed by @kalleep

  • Fix #953. noRedeclare no longer reports type parameters with the same name in different mapped types as redeclarations. Contributed by @Conaclos

Fix #608. useExhaustiveDependencies no longer repports missing dependencies for React hooks without dependency array. Contributed by @kalleep

  • Remove the CLI options from the lsp-proxy, as they were never meant to be passed to that command. Contributed by @ematipico

  • Add option --config-path to lsp-proxy and start commands. It’s now possible to tell the Daemon server to load biome.json from a custom path. Contributed by @ematipico

  • Add option --diagnostic-level. It lets users control the level of diagnostics printed by the CLI. Possible values are: "info", "warn", and "hint". Contributed by @simonxabris

  • Add option --line-feed to the format command. Contributed by @SuperchupuDev

  • Add option --bracket-same-line to the format command. Contributed by @faultyserve

  • Add option --bracket-spacing to the format command. Contributed by @faultyserve

  • Fix the command format, now it returns a non-zero exit code when if there pending diffs. Contributed by @ematipico
  • Add the configuration formatter.lineFeed. It allows changing the type of line endings. Contributed by @SuperchupuDev

  • Add the configuration javascript.formatter.bracketSameLine. It allows controlling whether ending > of a multi-line JSX element should be on the last attribute line or not. #627. Contributed by @faultyserver

  • Add the configuration javascript.formatter.bracketSpacing. It allows controlling whether spaces are inserted around the brackets of object literals. #627. Contributed by @faultyserver

  • Fix #832, the formatter no longer keeps an unnecessary trailing comma in type parameter lists. Contributed by @Conaclos

    class A<T,> {}
    class A<T> {}
  • Fix #301, the formatter should not break before the in keyword. Contributed by @ematipico

The following rules are now recommended:

The following rules are now deprecated:

  • Add noDefaultExport which disallows export default. Contributed by @Conaclos

  • Add noAriaHiddenOnFocusable which reports hidden and focusable elements. Contributed by @vasucp1207

  • Add noImplicitAnyLet that reports variables declared with let and without initialization and type annotation. Contributed by @TaKO8Ki and @b4s36t4

  • Add useAwait that reports async functions that don’t use an await expression.

  • Add useValidAriaRole. Contributed by @vasucp1207

  • Add useRegexLiterals that suggests turning call to the regex constructor into regex literals. COntributed by @Yuiki

  • Fix #639 by ignoring unused TypeScript’s mapped key. Contributed by @Conaclos

  • Fix #565 by handling several infer with the same name in extends clauses of TypeScript’s conditional types. Contributed by @Conaclos

Fix #653. noUnusedImports now correctly removes the entire line where the unused import is. Contributed by @Conaclos

  • Fix #607 useExhaustiveDependencies, ignore optional chaining, Contributed by @msdlisper

  • Fix #676, by using the correct node for the "noreferrer" when applying the code action. Contributed by @ematipico

  • Fix #455. The CLI can now print complex emojis to the console correctly.

Fix #727. noInferrableTypes now correctly keeps type annotations when the initialization expression is null. Contributed by @Conaclos

Fix #784, noSvgWithoutTitle fixes false-positives to aria-label and reports svg’s role attribute is implicit. Contributed by @unvalley

  • Fix #846 that erroneously parsed <const T,>() => {} as a JSX tag instead of an arrow function when both TypeScript and JSX are enabled.
  • Fix #604 which made noConfusingVoidType report false positives when the void type is used in a generic type parameter. Contributed by @unvalley
  • Fix how overrides behave. Now ignore and include apply or not the override pattern, so they override each other. Now the options inside overrides override the top-level options.
  • Bootstrap the logger only when needed. Contributed by @ematipico
  • Fix how overrides are run. The properties ignore and include have different semantics and only apply/not apply an override. Contributed by @ematipico
  • Fix #592, by changing binary resolution in the IntelliJ plugin. Contributed by @Joshuabaker2
  • Apply the correct layout when the right hand of an assignment expression is an await expression or a yield expression. Contributed by @ematipico

  • Fix #303, where nested arrow functions didn’t break. Contributed by @victor-teles

  • Fix #175 which made noRedeclare report index signatures using the name of a variable in the parent scope.

  • Fix #557 which made noUnusedImports report imported types used in typeof expression. Contributed by @Conaclos

  • Fix #576 by removing some erroneous logic in noSelfAssign. Contributed by @ematipico

  • Fix #861 that made noUnusedVariables always reports the parameter of a non-parenthesize arrow function as unused.

  • Fix #595 by updating unsafe-apply logic to avoid unexpected errors in noUselessFragments. Contributed by @nissy-dev

  • Fix #591 which made noRedeclare report type parameters with identical names but in different method signatures. Contributed by @Conaclos

  • Support more a11y roles and fix some methods for a11y lint rules Contributed @nissy-dev

  • Fix #609 useExhaustiveDependencies, by removing useContext, useId and useSyncExternalStore from the known hooks. Contributed by @msdlisper

  • Fix useExhaustiveDependencies, by removing useContext, useId and useSyncExternalStore from the known hooks. Contributed by @msdlisper

  • Fix #871 and #610. Now useHookAtTopLevel correctly handles nested functions. Contributed by @arendjr

  • The options of the rule useHookAtTopLevel are deprecated and will be removed in Biome 2.0. The rule now determines the hooks using the naming convention set by React.

    {
    "linter": {
    "rules": {
    "correctness": {
    "useHookAtTopLevel": "error",
    "useHookAtTopLevel": {
    "level": "error",
    "options": {
    "hooks": [
    {
    "name": "useLocation",
    "closureIndex": 0,
    "dependenciesIndex": 1
    },
    { "name": "useQuery", "closureIndex": 1, "dependenciesIndex": 0 }
    ]
    }
    }
    }
    }
    }
    }
  • Support RegExp v flag. Contributed by @nissy-dev
  • Improve error messages. Contributed by @ematipico
  • Fix rage command, now it doesn’t print info about running servers. Contributed by @ematipico
  • Fix #552, where the formatter isn’t correctly triggered in Windows systems. Contributed by @victor-teles
  • Import sorting is safe to apply now, and it will be applied when running check --apply instead of check --apply-unsafe.

  • Import sorting now handles Bun imports bun:<name>, absolute path imports /<path>, and Node’s subpath imports #<name>. See our documentation for more details. Contributed by @Conaclos

  • Fix #319. The command biome lint now shows the correct options. Contributed by @ematipico
  • Fix #312. Running biome --version now exits with status code 0 instead of 1. Contributed by @nhedger
  • Fix a bug where the extends functionality doesn’t carry over organizeImports.ignore. Contributed by @ematipico
  • The CLI now returns the original content when using stdin and the original content doesn’t change. Contributed by @ematipico
  • Add support for BIOME_BINARY environment variable to override the location of the binary. Contributed by @ematipico

  • Add option --indent-width, and deprecated the option --indent-size. Contributed by @ematipico

  • Add option --javascript-formatter-indent-width, and deprecated the option --javascript-formatter-indent-size. Contributed by @ematipico

  • Add option --json-formatter-indent-width, and deprecated the option --json-formatter-indent-size. Contributed by @ematipico

  • Add option --daemon-logs to biome rage. The option is required to view Biome daemon server logs. Contributed by @unvalley

  • Add support for logging. By default, Biome doesn’t log anything other than diagnostics. Logging can be enabled with the new option --log-level:

    Terminal window
    biome format --log-level=info ./src

    There are four different levels of logging, from the most verbose to the least verbose: debug, info, warn and error. Here’s how an INFO log will look like:

    2023-10-05T08:27:01.954727Z INFO Analyze file ./website/src/playground/components/Resizable.tsx
    at crates/biome_service/src/file_handlers/javascript.rs:298 on biome::worker_5
    in Pulling diagnostics with categories: RuleCategories(SYNTAX)
    in Processes formatting with path: "./website/src/playground/components/Resizable.tsx"
    in Process check with path: "./website/src/playground/components/Resizable.tsx"

    You can customize how the log will look like with a new option --log-kind. The supported kinds are: pretty, compact and json.

    pretty is the default logging. Here’s how a compact log will look like:

    2023-10-05T08:29:04.864247Z INFO biome::worker_2 Process check:Processes linting:Pulling diagnostics: crates/biome_service/src/file_handlers/javascript.rs: Analyze file ./website/src/playground/components/Resizable.tsx path="./website/src/playground/components/Resizable.tsx" path="./website/src/playground/components/Resizable.tsx" categories=RuleCategories(LINT)
    2023-10-05T08:29:04.864290Z INFO biome::worker_7 Process check:Processes formatting: crates/biome_service/src/file_handlers/javascript.rs: Format file ./website/src/playground/components/Tabs.tsx path="./website/src/playground/components/Tabs.tsx" path="./website/src/playground/components/Tabs.tsx"
    2023-10-05T08:29:04.879332Z INFO biome::worker_2 Process check:Processes formatting:Pulling diagnostics: crates/biome_service/src/file_handlers/javascript.rs: Analyze file ./website/src/playground/components/Resizable.tsx path="./website/src/playground/components/Resizable.tsx" path="./website/src/playground/components/Resizable.tsx" categories=RuleCategories(SYNTAX)
    2023-10-05T08:29:04.879383Z INFO biome::worker_2 Process check:Processes formatting: crates/biome_service/src/file_handlers/javascript.rs: Format file ./website/src/playground/components/Resizable.tsx path="./website/src/playground/components/Resizable.tsx" path="./website/src/playground/components/Resizable.tsx"
  • Deprecated the environment variable ROME_BINARY. Use BIOME_BINARY instead. Contributed by @ematipico
  • Biome doesn’t check anymore the presence of the .git folder when VCS support is enabled. Contributed by @ematipico
  • biome rage doesn’t print the logs of the daemon, use biome rage --daemon-logs to print them. Contributed by @unvalley
  • Add option formatter.indentWidth, and deprecated the option formatter.indentSize. Contributed by @ematipico

  • Add option javascript.formatter.indentWidth, and deprecated the option javascript.formatter.indentSize. Contributed by @ematipico

  • Add option json.formatter.indentWidth, and deprecated the option json.formatter.indentSize. Contributed by @ematipico

  • Add option include to multiple sections of the configuration

    • files.include;
    • formatter.include;
    • linter.include;
    • organizeImports.include; When include and ignore are both specified, ignore takes precedence over include
  • Add option overrides, where users can modify the behaviour of the tools for certain files or paths.

    For example, it’s possible to modify the formatter lineWidth, and even quoteStyle for certain files that are included in glob path generated/**:

    {
    "formatter": {
    "lineWidth": 100
    },
    "overrides": [
    {
    "include": ["generated/**"],
    "formatter": {
    "lineWidth": 160
    },
    "javascript": {
    "formatter": {
    "quoteStyle": "single"
    }
    }
    }
    ]
    }

    Or, you can disable certain rules for certain path, and disable the linter for other paths:

    {
    "linter": {
    "enabled": true,
    "rules": {
    "recommended": true
    }
    },
    "overrides": [
    {
    "include": ["lib/**"],
    "linter": {
    "rules": {
    "suspicious": {
    "noDebugger": "off"
    }
    }
    }
    },
    {
    "include": ["shims/**"],
    "linter": {
    "enabled": false
    }
    }
    ]
    }
  • Fix #343, extends was incorrectly applied to the biome.json file. Contributed by @ematipico
  • Fix #404. Biome intellij plugin now works on Windows. Contributed by @victor-teles

  • Fix #402. Biome format on intellij plugin now recognize biome.json. Contributed by @victor-teles

  • Use OnceCell for the Memoized memory because that’s what the RefCell<Option> implemented. Contributed by @denbezrukov

The following rules are now recommended:

  • Add noEmptyCharacterClassInRegex rule. The rule reports empty character classes and empty negated character classes in regular expression literals. Contributed by @Conaclos

  • Add noMisleadingInstantiator rule. The rule reports the misleading use of the new and constructor methods. Contributed by @unvalley

  • Add noUselessElse rule. The rule reports else clauses that can be omitted because their if branches break. Contributed by @Conaclos

  • Add noUnusedImports rule. The rule reports unused imports and suggests removing them. Contributed by @Conaclos

    noUnusedVariables reports also unused imports, but don’t suggest their removal. Once noUnusedImports stabilized, noUnusedVariables will not report unused imports.

  • Add useShorthandAssign rule. The rule enforce use of shorthand operators that combine variable assignment and some simple mathematical operations. For example, x = x + 4 can be shortened to x += 4. Contributed by @victor-teles

  • Add useAsConstAssertion rule. The rule enforce use of as const assertion to infer literal types. Contributed by @unvalley

  • Add noMisrefactoredShorthandAssign rule. The rule reports shorthand assigns when variable appears on both sides. For example x += x + b Contributed by @victor-teles

  • Add noApproximativeNumericConstant rule. Contributed by @nikeee

Add noInteractiveElementToNoninteractiveRole rule. The rule enforces the non-interactive ARIA roles are not assigned to interactive HTML elements. Contributed by @nissy-dev

  • Add useAriaActivedescendantWithTabindex rule. The rule enforces that tabIndex is assigned to non-interactive HTML elements with aria-activedescendant. Contributed by @nissy-dev

  • Add noUselessLoneBlockStatements rule. The rule reports standalone blocks that don’t include any lexical scoped declaration. Contributed by @emab

  • Add noInvalidNewBuiltin rule. The rule reports use of new on Symbol and BigInt. Contributed by @lucasweng

Fix #294. noConfusingVoidType no longer reports false positives for return types. Contributed by @b4s36t4

Fix #313. noRedundantUseStrict now keeps leading comments.

Fix #383. noMultipleSpacesInRegularExpressionLiterals now provides correct code fixes when consecutive spaces are followed by a quantifier. Contributed by @Conaclos

Fix #397. useNumericLiterals now provides correct code fixes for signed numbers. Contributed by @Conaclos

  • Fix 452. The linter panicked when it met a malformed regex (a regex not ending with a slash).

  • Fix #104. We now correctly handle types and values with the same name.

  • Fix #243 a false positive case where the incorrect scope was defined for the infer type in rule noUndeclaredVariables. Contributed by @denbezrukov

  • Fix #322, now noSelfAssign correctly handles literals inside call expressions.

  • Changed how noSelfAssign behaves. The rule is not triggered anymore on function calls. Contributed by @ematipico

  • Enhance diagnostic for infer type handling in the parser. The ‘infer’ keyword can only be utilized within the ’ extends’ clause of a conditional type. Using it outside this context will result in an error. Ensure that any type declarations using ‘infer’ are correctly placed within the conditional type structure to avoid parsing issues. Contributed by @denbezrukov

  • Add support for parsing trailing commas inside JSON files:

    {
    "json": {
    "parser": {
    "allowTrailingCommas": true
    }
    }
    }

    Contributed by @nissy-dev

  • Fix a condition where import sorting wasn’t applied when running biome check --apply
  • Fix an edge case where the formatter language configuration wasn’t picked.
  • Fix the configuration schema, where json.formatter properties weren’t transformed in camel case.
  • Add new options to customize the behaviour the formatter based on the language of the file
    • --json-formatter-enabled
    • --json-formatter-indent-style
    • --json-formatter-indent-size
    • --json-formatter-line-width
    • --javascript-formatter-enabled
    • --javascript-formatter-indent-style
    • --javascript-formatter-indent-size
    • --javascript-formatter-line-width
  • Fix a bug where --errors-on-warning didn’t work when running biome ci command.
  • Add new options to customize the behaviour of the formatter based on the language of the file
    • json.formatter.enabled
    • json.formatter.indentStyle
    • json.formatter.indentSize
    • json.formatter.lineWidth
    • javascript.formatter.enabled
    • javascript.formatter.indentStyle
    • javascript.formatter.indentSize
    • javascript.formatter.lineWidth

New rules are incubated in the nursery group. Once stable, we promote them to a stable group. The following rules are promoted:

  • Add noConfusingVoidType rule. The rule reports the unusual use of the void type. Contributed by @shulandmimi
  • Remove noConfusingArrow

    Code formatters, such as prettier and Biome, always adds parentheses around the parameter or the body of an arrow function. This makes the rule useless.

    Contributed by @Conaclos

  • noFallthroughSwitchClause now relies on control flow analysis to report most of the switch clause fallthrough. Contributed by @Conaclos

  • noAssignInExpressions no longer suggest code fixes. Most of the time the suggestion didn’t match users’ expectations. Contributed by @Conaclos

  • noUselessConstructor no longer emits safe code fixes. Contributed by @Conaclos

    All code fixes are now emitted as unsafe code fixes. Removing a constructor can change the behavior of a program.

  • useCollapsedElseIf now only provides safe code fixes. Contributed by @Conaclos

  • noUnusedVariables now reports more cases.

    The rule is now able to ignore self-writes. For example, the rule reports the following unused variable:

    let a = 0;
    a++;
    a += 1;

    The rule is also capable of detecting an unused declaration that uses itself. For example, the rule reports the following unused interface:

    interface I {
    instance(): I
    }

    Finally, the rule now ignores all TypeScript declaration files, including global declaration files.

    Contributed by @Conaclos

  • Fix #182, making useLiteralKeys retains optional chaining. Contributed by @denbezrukov

  • Fix #168, fix useExhaustiveDependencies false positive case when stable hook is on a new line. Contributed by @denbezrukov

  • Fix #137, fix noRedeclare false positive case with TypeScript module declaration:

    declare module '*.gif' {
    const src: string;
    }
    declare module '*.bmp' {
    const src: string;
    }

    Contributed by @denbezrukov

  • Fix #258, fix noUselessFragments the case where the rule removing an assignment. Contributed by @denbezrukov

  • Fix #266, where complexity/useLiteralKeys emitted a code action with an invalid AST. Contributed by @ematipico

  • Fix #105, removing false positives reported by noUnusedVariables.

    The rule no longer reports the following used variable:

    const a = f(() => a);

    Contributed by @Conaclos

  • Improve server binary resolution when using certain package managers, notably pnpm.

    The new strategy is to point to node_modules/.bin/biome path, which is consistent for all package managers.

  • Fix a case where an empty JSON file would cause the LSP server to crash. Contributed by @ematipico
  • useNamingConvention now accepts import namespaces in PascalCase and rejects export namespaces in CONSTANT_CASE.

    The following code is now valid:

    import * as React from "react";

    And the following code is now invalid:

    export * as MY_NAMESPACE from "./lib.js";

    Contributed by @Conaclos

  • noUselessConstructor now ignores decorated classes and decorated parameters. The rule now gives suggestions instead of safe fixes when parameters are annotated with types. Contributed by @Conaclos

  • The diagnostic for // rome-ignore suppression comment should not be a warning. A warning could block the CI, marking a gradual migration difficult. The code action that changes // rome-ignore to // biome-ignore is disabled as consequence. Contributed by @ematipico
  • Add a code action to replace rome-ignore with biome-ignore. Use biome check --apply-unsafe to update all the comments. The action is not bulletproof, and it might generate unwanted code, that’s why it’s unsafe action. Contributed by @ematipico
  • Biome now reports a diagnostics when a rome.json file is found.
  • biome migrate --write creates biome.json from rome.json, but it won’t delete the rome.json file. Contributed by @ematipico
  • Biome uses biome.json first, then it attempts to use rome.json.
  • Fix a case where Biome couldn’t compute correctly the ignored files when the VSC integration is enabled. Contributed by @ematipico
  • The LSP now uses its own socket and won’t rely on Biome’s socket. This fixes some cases where users were seeing multiple servers in the rage output.
  • You can use // biome-ignore as suppression comment.
  • The // rome-ignore suppression is deprecated.
  • Add useCollapsedElseIf rule. This new rule requires merging an else and an if, if the if statement is the only statement in the else block. Contributed by @n-gude
  • useTemplate now reports all string concatenations.

    Previously, the rule ignored concatenation of a value and a newline or a backquote. For example, the following concatenation was not reported:

    v + "\n";
    "`" + v + "`";

    The rule now reports these cases and suggests the following code fixes:

    v + "\n";
    `${v}\n`;
    v + "`";
    `\`${v}\``;

    Contributed by @Conaclos

  • useExponentiationOperator suggests better code fixes.

    The rule now preserves any comment preceding the exponent, and it preserves any parenthesis around the base or the exponent. It also adds spaces around the exponentiation operator **, and always adds parentheses for pre- and post-updates.

    Math.pow(a++, /**/ (2))
    (a++) ** /**/ (2)

    Contributed by @Conaclos

  • You can use // biome-ignore as suppression comment.

  • The // rome-ignore suppression is deprecated.

  • Fix #80, making noDuplicateJsxProps case-insensitive.

    Some frameworks, such as Material UI, rely on the case-sensitivity of JSX properties. For example, TextField has two properties with the same name, but distinct cases:

    <TextField inputLabelProps="" InputLabelProps=""></TextField>

    Contributed by @Conaclos

  • Fix #138

    noCommaOperator now correctly ignores all use of comma operators inside the update part of a for loop. The following code is now correctly ignored:

    for (
    let i = 0, j = 1, k = 2;
    i < 100;
    i++, j++, k++
    ) {}

    Contributed by @Conaclos

  • Fix rome#4713.

    Previously, useTemplate made the following suggestion:

    a + b + "px"
    `${a}${b}px`

    This breaks code where a and b are numbers.

    Now, the rule makes the following suggestion:

    a + b + "px"
    `${a + b}px`

    Contributed by @Conaclos

  • Fix rome#4109

    Previously, useTemplate suggested an invalid code fix when a leading or trailing single-line comment was present:

    // leading comment
    1 /* inner comment */ + "+" + 2 // trailing comment
    `${// leading comment
    1 /* inner comment */}+${2 //trailing comment}` // trailing comment

    Now, the rule correctly handles this case:

    // leading comment
    1 + "+" + 2 // trailing comment
    `${1}+${2}` // trailing comment

    As a sideeffect, the rule also suggests the removal of any inner comments.

    Contributed by @Conaclos

  • Fix rome#3850

    Previously useExponentiationOperator suggested invalid code in a specific edge case:

    1 +Math.pow(++a, 2)
    1 +++a**2

    Now, the rule properly adds parentheses:

    1 +Math.pow(++a, 2)
    1 +(++a) ** 2

    Contributed by @Conaclos

  • Fix #106

    noUndeclaredVariables now correctly recognizes some TypeScript types such as Uppercase.

    Contributed by @Conaclos

  • Fix rome#4616

    Previously noUnreachableSuper reported valid codes with complex nesting of control flow structures.

    Contributed by @Conaclos

  • The organize imports feature now groups import statements by “distance”.

    Modules “farther” from the user are put on the top, and modules “closer” to the user are placed on the bottom. Check the documentation for more information about it.

  • The organize imports tool is enabled by default. If you don’t want to use it, you need to disable it explicitly:

    {
    "organizeImports": {
    "enabled": false
    }
    }
  • The CLI now exists with an error when there’s an error inside the configuration.

    Previously, biome would raise warnings and continue the execution by applying its defaults.

    This could have been better for users because this could have created false positives in linting or formatted code with a configuration that wasn’t the user’s.

  • The command biome check now shows formatter diagnostics when checking the code.

    The diagnostics presence will result in an error code when the command finishes.

    This aligns with semantic and behaviour meant for the command biome check.

  • init command emits a biome.json file;

  • Fix #4670, don’t crash at empty default export.

  • Fix #4556, which correctly handles new lines in the .gitignore file across OS.

  • Add a new option to ignore unknown files --files-ignore-unknown:

    Terminal window
    biome format --files-ignore-unknown ./src

    Doing so, Biome won’t emit diagnostics for files that doesn’t know how to handle.

  • Add the new option --no-errors-on-unmatched:

    Terminal window
    biome format --no-errors-on-unmatched ./src

    Biome doesn’t exit with an error code if no files were processed in the given paths.

  • Fix the diagnostics emitted when running the biome format command.

  • Biome no longer warns when discovering (possibly infinite) symbolic links between directories.

    This fixes #4193 which resulted in incorrect warnings when a single file or directory was pointed at by multiple symbolic links. Symbolic links to other symbolic links do still trigger warnings if they are too deeply nested.

  • Introduced a new command called biome lint, which will only run lint rules against the code base.

  • Biome recognizes known files as “JSON files with comments allowed”:

    • typescript.json;
    • tsconfig.json;
    • jsconfig.json;
    • tslint.json;
    • babel.config.json;
    • .babelrc.json;
    • .ember-cli;
    • typedoc.json;
    • .eslintrc.json;
    • .eslintrc;
    • .jsfmtrc;
    • .jshintrc;
    • .swcrc;
    • .hintrc;
    • .babelrc;
  • Add support for biome.json;

  • Add a new option to ignore unknown files:

    {
    "files": {
    "ignoreUnknown": true
    }
    }

    Doing so, Biome won’t emit diagnostics for file that it doesn’t know how to handle.

  • Add a new "javascript" option to support the unsafe/experimental parameter decorators:

    {
    "javascript": {
    "parser": {
    "unsafeParameterDecoratorsEnabled": true
    }
    }
    }
  • Add a new "extends" option, useful to split the configuration file in multiple files:

    {
    "extends": ["../sharedFormatter.json", "linter.json"]
    }

    The resolution of the files is file system based, Biome doesn’t know how to resolve dependencies yet.

  • The commands biome check and biome lint now show the remaining diagnostics even when --apply-safe or --apply-unsafe are passed.

  • Fix the commands biome check and biome lint, they won’t exit with an error code if no error diagnostics are emitted.

  • Add a new option --error-on-warnings, which instructs Biome to exit with an error code when warnings are emitted.

    Terminal window
    biome check --error-on-wanrings ./src
  • Add a configuration to enable parsing comments inside JSON files:

    {
    "json": {
    "parser": {
    "allowComments": true
    }
    }
    }
  • The Biome LSP can now show diagnostics belonging to JSON lint rules.

  • The Biome LSP no longer applies unsafe quickfixes on-save when editor.codeActionsOnSave.quickfix.biome is enabled.

  • Fix #4564; files too large don’t emit errors.

  • The Biome LSP sends client messages when files are ignored or too big.

  • Add a new option called --jsx-quote-style.

    This option lets you choose between single and double quotes for JSX attributes.

  • Add the option --arrow-parentheses.

    This option allows setting the parentheses style for arrow functions.

  • The JSON formatter can now format .json files with comments.

  • Remove complexity/noExtraSemicolon (#4553)

    The Biome formatter takes care of removing extra semicolons. Thus, there is no need for this rule.

  • Remove useCamelCase

    Use useNamingConvention instead.

New rules are promoted, please check #4750 for more details:

The following rules are now recommended:

**- noUselessFragments

  • Add new TypeScript globals (AsyncDisposable, Awaited, DecoratorContext, and others) 4643.

  • noRedeclare: allow redeclare of index signatures are in different type members #4478

Improve noConsoleLog, noGlobalObjectCalls, useIsNan, and useNumericLiterals by handling globalThis and window namespaces.

For instance, the following code is now reported by noConsoleLog:

globalThis.console.log("log")
  • Improve noDuplicateParameters to manage constructor parameters.

  • Improve noInnerDeclarations

    Now, the rule doesn’t report false-positives about ambient TypeScript declarations. For example, the following code is no longer reported by the rule:

    declare var foo;
  • Improve useEnumInitializers

    The rule now reports all uninitialized members of an enum in a single diagnostic.

    Moreover, ambient enum declarations are now ignored. This avoids reporting ambient enum declarations in TypeScript declaration files.

    declare enum Weather {
    Rainy,
    Sunny,
    }
  • Relax noBannedTypes and improve documentation

    The rule no longer reports a user type that reuses a banned type name. The following code is now allowed:

    import { Number } from "a-lib";
    declare const v: Number;

    The rule now allows the use of the type {} to denote a non-nullable generic type:

    function f<T extends {}>(x: T) {
    assert(x != null);
    }

    And in a type intersection for narrowing a type to its non-nullable equivalent type:

    type NonNullableMyType = MyType & {};
  • Improve noConstantCondition

    The rule now allows while(true). This recognizes a common pattern in the web community:

    while (true) {
    if (cond) {
    break;
    }
    }
  • Improve the diagnostic and the code action of useDefaultParameterLast.

    The diagnostic now reports the last required parameter which should precede optional and default parameters.

    The code action now removes any whitespace between the parameter name and its initialization.

  • Relax noConfusingArrow

    All arrow functions that enclose its parameter with parenthesis are allowed. Thus, the following snippet no longer trigger the rule:

    var x = (a) => 1 ? 2 : 3;

    The following snippet still triggers the rule:

    var x = a => 1 ? 2 : 3;
  • Relax useLiteralEnumMembers

    Enum members that refer to previous enum members are now allowed. This allows a common pattern in enum flags like in the following example:

    enum FileAccess {
    None = 0,
    Read = 1,
    Write = 1 << 1,
    All = Read | Write,
    }

    Arbitrary numeric constant expressions are also allowed:

    enum FileAccess {
    None = 0,
    Read = 2**0,
    Write = 2**1,
    All = Read | Write,
    }
  • Improve useLiteralKeys.

    Now, the rule suggests simplifying computed properties to string literal properties:

    {
    ["1+1"]: 2,
    "1+1": 2,
    }

    It also suggests simplifying string literal properties to static properties:

    {
    "a": 0,
    a: 0,
    }

    These suggestions are made in object literals, classes, interfaces, and object types.

  • Improve noNewSymbol.

    The rule now handles cases where Symbol is namespaced with the global globalThis or window.

  • The rules useExhaustiveDependencies and useHookAtTopLevel accept a different shape of options

    Old configuration:

    {
    "linter": {
    "rules": {
    "nursery": {
    "useExhaustiveDependencies": {
    "level": "error",
    "options": {
    "hooks": [
    ["useMyEffect", 0, 1]
    ]
    }
    }
    }
    }
    }
    }

    New configuration:

    {
    "linter": {
    "rules": {
    "nursery": {
    "useExhaustiveDependencies": {
    "level": "error",
    "options": {
    "hooks": [
    {
    "name": "useMyEffect",
    "closureIndex": 0,
    "dependenciesIndex": 1
    }
    ]
    }
    }
    }
    }
    }
    }
  • noRedundantUseStrict check only 'use strict' directive to resolve false positive diagnostics.

    React introduced new directives, “use client” and “use server”. The rule raises false positive errors about these directives.

  • Fix a crash in the NoParameterAssign rule that occurred when there was a bogus binding. #4323

  • Fix useExhaustiveDependencies in the following cases #4330:

    • when the first argument of hooks is a named function
    • inside an export default function
    • for React.use hooks
  • Fix noInvalidConstructorSuper that erroneously reported generic parents #4624.

  • Fix noDuplicateCase that erroneously reported as equals the strings literals "'" and '"' #4706.

  • Fix NoUnreachableSuper’s false positive diagnostics (#4483) caused to nested if statement.

    The rule no longer reports This constructor calls super() in a loop when using nested if statements in a constructor.

  • Fix useHookAtTopLevel’s false positive diagnostics (#4637)

    The rule no longer reports false positive diagnostics when accessing properties directly from a hook and calling a hook inside function arguments.

  • Fix noUselessConstructor which erroneously reported constructors with default parameters rome#4781

  • Fix noUselessFragments’s panics when running biome check --apply-unsafe (#4637)

    This rule’s code action emits an invalid AST, so I fixed using JsxString instead of JsStringLiteral

  • Fix noUndeclaredVariables’s false positive diagnostics (#4675)

    The semantic analyzer no longer handles this reference identifier.

  • Fix noUnusedVariables’s false positive diagnostics (#4688)

    The semantic analyzer handles ts export declaration clause correctly.

  • Add support for decorators in class method parameters, example:

    class AppController {
    get(@Param() id) {}
    // ^^^^^^^^ new supported syntax
    }

    This syntax is only supported via configuration, because it’s a non-standard syntax.

    {
    "javascript": {
    "parser": {
    "unsafeParameterDecoratorsEnabled": true
    }
    }
    }
  • Add support for parsing comments inside JSON files:

    {
    "json": {
    "parser": {
    "allowComments": true
    }
    }
    }
  • Add support for the new using syntax

    const using = resource.lock();