noDefaultExport

Diagnostic Category: lint/style/noDefaultExport

JavaScript (and super languages)

Since: v1.4.0 Sources:

Same as: import/no-default-export

Description

Disallow default exports.

Default exports cannot be easily discovered inside an editor: They cannot be suggested by the editor when the user tries to import a name.

Also, default exports don’t encourage consistency over a code base: the module that imports the default export must choose a name. It is likely that different modules use different names.

Moreover, default exports encourage exporting an object that acts as a namespace. This is a legacy pattern used to mimic CommonJS modules.

For all these reasons, a team may want to disallow default exports.

Note that this rule disallows only default exports in EcmaScript Module. It ignores CommonJS default exports.

Examples

Invalid

export default function f() {};

code-block.js:1:8 lint/style/noDefaultExport ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Avoid default exports.
  
  > 1 │ export default function f() {};
      │        ^^^^^^^
    2 │ 
  
  ℹ Default exports cannot be easily discovered inside an editor and don’t encourage the use of consistent names through a code base.
  
  ℹ Use a named export instead.

export default class C {};

code-block.js:1:8 lint/style/noDefaultExport ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Avoid default exports.
  
  > 1 │ export default class C {};
      │        ^^^^^^^
    2 │ 
  
  ℹ Default exports cannot be easily discovered inside an editor and don’t encourage the use of consistent names through a code base.
  
  ℹ Use a named export instead.

export default {
    f() {},
    g() {},
};

code-block.js:1:8 lint/style/noDefaultExport ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Avoid default exports.
  
  > 1 │ export default {
      │        ^^^^^^^
    2 │     f() {},
    3 │     g() {},
  
  ℹ Default exports cannot be easily discovered inside an editor and don’t encourage the use of consistent names through a code base.
  
  ℹ Use a named export instead.

export { X as default };

code-block.js:1:15 lint/style/noDefaultExport ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ⚠ Avoid default exports.
  
  > 1 │ export { X as default };
      │               ^^^^^^^
    2 │ 
  
  ℹ Default exports cannot be easily discovered inside an editor and don’t encourage the use of consistent names through a code base.
  
  ℹ Use a named export instead.

Valid

export function f () {};
export class C {};
export { default as X } from "mod";

module.exports = class {};

How to configure

{
  "linter": {
    "rules": {
      "style": {
        "noDefaultExport": "error"
      }
    }
  }
}