noUselessQualifier (JavaScript)

Language JavaScript (and super languages)

Summary

Diagnostic Category: lint/nursery/noUselessQualifier
This rule has an unsafe fix.
The default severity of this rule is information.
Sources:
- Same as @typescript-eslint/no-unnecessary-qualifier

How to configure

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{
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  "linter": {
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    "rules": {
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      "nursery": {
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        "noUselessQualifier": "error"
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      }
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    }
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  }
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}

Description

Disallow unnecessary namespace and enum qualifiers.

The members of a TypeScript namespace or enum are usually accessed through the name of the namespace or enum, for example Direction.Up. The Direction. part is called a qualifier.

Inside the namespace or enum itself, the members can be used by their name alone, so the qualifier only repeats what is already known.

This rule doesn’t report a qualifier when the member name alone would refer to something else, for example because a local variable has the same name.

Examples

Invalid

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enum Direction {
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    Up,
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    Down = Direction.Up + 1,
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}

code-block.ts:3:12 lint/nursery/noUselessQualifier  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ The qualifier before Up is unnecessary.
  
    1 │ enum Direction {
    2 │     Up,
  > 3 │     Down = Direction.Up + 1,
      │            ^^^^^^^^^
    4 │ }
    5 │ 
  
  ℹ Inside a namespace or an enum, its members can be used by their name alone, so the qualifier only repeats what is already known.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
  
  ℹ Unsafe fix: Remove the qualifier.
  
    1 1 │   enum Direction {
    2 2 │       Up,
    3   │ - ····Down·=·Direction.Up·+·1,
      3 │ + ····Down·=·Up·+·1,
    4 4 │   }
    5 5 │

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namespace Shapes {
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    export type Point = { x: number; y: number };
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    const origin: Shapes.Point = { x: 0, y: 0 };
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}

code-block.ts:3:19 lint/nursery/noUselessQualifier  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ The qualifier before Point is unnecessary.
  
    1 │ namespace Shapes {
    2 │     export type Point = { x: number; y: number };
  > 3 │     const origin: Shapes.Point = { x: 0, y: 0 };
      │                   ^^^^^^
    4 │ }
    5 │ 
  
  ℹ Inside a namespace or an enum, its members can be used by their name alone, so the qualifier only repeats what is already known.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
  
  ℹ Unsafe fix: Remove the qualifier.
  
    1 1 │   namespace Shapes {
    2 2 │       export type Point = { x: number; y: number };
    3   │ - ····const·origin:·Shapes.Point·=·{·x:·0,·y:·0·};
      3 │ + ····const·origin:·Point·=·{·x:·0,·y:·0·};
    4 4 │   }
    5 5 │

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namespace Config {
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    export const timeout = 1000;
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    export function getTimeout() {
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        return Config.timeout;
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    }
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}

code-block.ts:4:16 lint/nursery/noUselessQualifier  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ The qualifier before timeout is unnecessary.
  
    2 │     export const timeout = 1000;
    3 │     export function getTimeout() {
  > 4 │         return Config.timeout;
      │                ^^^^^^
    5 │     }
    6 │ }
  
  ℹ Inside a namespace or an enum, its members can be used by their name alone, so the qualifier only repeats what is already known.
  
  ℹ This rule belongs to the nursery group, which means it is not yet stable and may change in the future. Visit https://biomejs.dev/linter/#nursery for more information.
  
  ℹ Unsafe fix: Remove the qualifier.
  
    2 2 │       export const timeout = 1000;
    3 3 │       export function getTimeout() {
    4   │ - ········return·Config.timeout;
      4 │ + ········return·timeout;
    5 5 │       }
    6 6 │   }

Valid

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enum Direction {
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    Up,
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    Down = Up + 1,
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}
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namespace Shapes {
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    export type Point = { x: number; y: number };
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    const origin: Point = { x: 0, y: 0 };
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}
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namespace Outer {
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    export type Id = number;
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    namespace Inner {
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        type Id = string;
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        // `Id` alone would refer to `Inner.Id`.
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        const id: Outer.Id = 0;
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    }
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}