Version History

Version 2.4.12 Latest

Patch Changes

#9376 9701a33 Thanks @dyc3! - Added the nursery/noIdenticalTestTitle lint rule. This rule disallows using the same title for two describe blocks or two test cases at the same nesting level.

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describe("foo", () => {});
2
describe("foo", () => {
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  // invalid: same title as previous describe block
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  test("baz", () => {});
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  test("baz", () => {}); // invalid: same title as previous test case
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});

#9889 7ae83f2 Thanks @dyc3! - Improved the diagnostics for useForOf to better explain the problem, why it matters, and how to fix it.

#9916 27dd7b1 Thanks @Jayllyz! - Added a new nursery rule noComponentHookFactories, that disallows defining React components or custom hooks inside other functions.

For example, the following snippets trigger the rule:

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function createComponent(label) {
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  function MyComponent() {
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    return <div>{label}</div>;
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  }
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  return MyComponent;
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}

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function Parent() {
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  function Child() {
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    return <div />;
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  }
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  return <Child />;
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}

#9980 098f1ff Thanks @ematipico! - Fixed #9941: Biome now emits a warning diagnostic when a file exceed the files.maxSize limit.
#9942 9956f1d Thanks @dyc3! - Fixed #9918: useConsistentTestIt no longer panics when applying fixes to chained calls such as test.for([])("x", () => {});.
#9891 4d9ac51 Thanks @dyc3! - Improved the noGlobalObjectCalls diagnostic to better explain why calling global objects like Math or JSON is invalid and how to fix it.
#9902 3f4d103 Thanks @ematipico! - Fixed #9901: the command lint --write is now idempotent when it’s run against HTML-ish files that contains scripts and styles.
#9891 4d9ac51 Thanks @dyc3! - Improved the noMultiStr diagnostic to explain why escaped multiline strings are discouraged and what to use instead.
#9966 322675e Thanks @siketyan! - Fixed #9113: Biome now parses and formats @media and other conditional blocks correctly inside embedded CSS snippets.
#9835 f8d49d9 Thanks @bmish! - The noFloatingPromises rule now detects floating promises through cross-module generic wrapper functions. Previously, patterns like export const fn = trace(asyncFn) — where trace preserves the function signature via a generic <F>(fn: F): F — were invisible to the rule when the wrapper was defined in a different file.
#9981 02bd8dd Thanks @siketyan! - Fixed #9975: Biome now parses nested CSS selectors correctly inside embedded snippets without requiring an explicit &.
#9949 e0ba71d Thanks @Netail! - Added the nursery rule useIframeSandbox, which enforces the sandbox attribute for iframe tags.

Invalid:
```
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<iframe></iframe>
```
#9913 d417803 Thanks @Netail! - Added the nursery rule noJsxNamespace, which disallows JSX namespace syntax.

Invalid:
```
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<ns:testcomponent />
```
#9892 e75d70e Thanks @dyc3! - Improved the noSelfCompare diagnostic to better explain why comparing a value to itself is suspicious and what to use for NaN checks.
#9861 2cff700 Thanks @dyc3! - Added the new nursery rule useVarsOnTop, which requires var declarations to appear at the top of their containing scope.

For example, the following code now triggers the rule:
```
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function f() {
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  doSomething();
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  var value = 1;
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}
```
#9892 e75d70e Thanks @dyc3! - Improved the noThenProperty diagnostic to better explain why exposing then can create thenable behavior and how to avoid it.
#9892 e75d70e Thanks @dyc3! - Improved the noShorthandPropertyOverrides diagnostic to explain why later shorthand declarations can unintentionally overwrite earlier longhand properties.
#9978 4847715 Thanks @mdevils! - Fixed #9744: useExhaustiveDependencies no longer reports false positives for variables obtained via object destructuring with computed keys, e.g. const { [KEY]: key1 } = props.
#9892 e75d70e Thanks @dyc3! - Improved the noRootType diagnostic to better explain that the reported root type is disallowed by project configuration and how to proceed.
#9927 7974ab7 Thanks @dyc3! - Added eslint-plugin-unicorn’s no-nested-ternary as a rule source for noNestedTernary
#9873 19ff706 Thanks @minseong0324! - noMisleadingReturnType now checks class methods, object methods, and getters in addition to functions.
#9888 362b638 Thanks @dyc3! - Updated metadata for biome migrate eslint to better reflect which ESLint rules are redundant versus unsupported versus unimplemented.
#9892 e75d70e Thanks @dyc3! - Improved the noAutofocus diagnostic to better explain why autofocus harms accessibility outside allowed modal contexts.
#9982 d6bdf4a Thanks @dyc3! - Improved performance of noMagicNumbers. Biome now maps ESLint no-magic-numbers sources more accurately during biome migrate eslint.
#9889 7ae83f2 Thanks @dyc3! - Improved the diagnostics for noConstantCondition to better explain the problem, why it matters, and how to fix it.
#9866 40bd180 Thanks @dyc3! - Added a new nursery rule noExcessiveSelectorClasses, which limits how many class selectors can appear in a single CSS selector.
#9796 f1c1363 Thanks @dyc3! - Added a new nursery rule useStringStartsEndsWith, which prefers startsWith() and endsWith() over verbose string prefix and suffix checks.

The rule uses type information, so it only reports on strings and skips array lookups such as items[0] === "a".
#9942 9956f1d Thanks @dyc3! - Fixed the safe fix for noSkippedTests so it no longer panics when rewriting skipped test function names such as xit(), xtest(), and xdescribe().
#9874 9e570d1 Thanks @minseong0324! - Type-aware lint rules now resolve members through Pick<T, K> and Omit<T, K> utility types.
#9909 0d0e611 Thanks @Netail! - Added the nursery rule useReactAsyncServerFunction, which requires React server actions to be async.

Invalid:
```
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function serverFunction() {
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  "use server";
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  // ...
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}
```
#9925 29accb3 Thanks @ematipico! - Fixed #9910: added support for parsing member expressions in Svelte directive properties. Biome now correctly parses directives like in:renderer.in|global, use:obj.action, and deeply nested forms like in:a.b.c|global.
#9904 e7775a5 Thanks @ematipico! - Fixed #9626: noUnresolvedImports no longer reports false positives for named imports from packages that have a corresponding @types/* package installed. For example, import { useState } from "react" with @types/react installed is now correctly recognised.
#9942 9956f1d Thanks @dyc3! - Fixed the safe fix for noFocusedTests so it no longer panics when rewriting focused test function names such as fit() and fdescribe().
#9577 c499f46 Thanks @tt-a1i! - Added the nursery rule useReduceTypeParameter. It flags type assertions on the initial value passed to Array#reduce and Array#reduceRight and recommends using a type parameter instead.
```
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// before: type assertion on initial value
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arr.reduce((sum, num) => sum + num, [] as number[]);
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// after: type parameter on the call
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arr.reduce<number[]>((sum, num) => sum + num, []);
```
#9895 1c8e1ef Thanks @Netail! - Added extra rule sources from react-xyz. biome migrate eslint should do a bit better detecting rules in your eslint configurations.
#9891 4d9ac51 Thanks @dyc3! - Improved the noInvalidUseBeforeDeclaration diagnostic to better explain why using a declaration too early is problematic and how to fix it.
#9889 7ae83f2 Thanks @dyc3! - Improved the diagnostics for noRedeclare to better explain the problem, why it matters, and how to fix it.
#9875 a951586 Thanks @minseong0324! - Type-aware lint rules now resolve members through Partial<T>, Required<T>, and Readonly<T> utility types, preserving optional, readonly, and nullable member flags.