noUselessSwitchCase

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JavaScript (and super languages)

Summary

Rule available since: v1.0.0
Diagnostic Category: lint/complexity/noUselessSwitchCase
This rule is recommended, which means is enabled by default.
This rule has an unsafe fix.
The default severity of this rule is information.
Sources:
- Same as unicorn/no-useless-switch-case

How to configure

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{
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  "linter": {
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    "rules": {
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      "complexity": {
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        "noUselessSwitchCase": "error"
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      }
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    }
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  }
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}

Description

Disallow useless case in switch statements.

A switch statement can optionally have a default clause.

The default clause will be still executed only if there is no match in the case clauses. An empty case clause that precedes the default clause is thus useless.

Examples

Invalid

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switch (foo) {
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    case 0:
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    default:
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        break;
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    case 1:
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        break;
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}

code-block.js:2:5 lint/complexity/noUselessSwitchCase  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Useless case clause.
  
    1 │ switch (foo) {
  > 2 │     case 0:
      │     ^^^^^^^
    3 │     default:
    4 │         break;
  
  ℹ because the default clause is present:
  
    1 │ switch (foo) {
    2 │     case 0:
  > 3 │     default:
      │     ^^^^^^^^
  > 4 │         break;
      │         ^^^^^^
    5 │     case 1:
    6 │         break;
  
  ℹ Unsafe fix: Remove the useless case.
  
    1 1 │   switch (foo) {
    2   │ - ····case·0:
    3 2 │       default:
    4 3 │           break;

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switch (foo) {
2
    default:
3
    case 0:
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        break;
5
    case 1:
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        break;
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}

code-block.js:3:5 lint/complexity/noUselessSwitchCase  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Useless case clause.
  
    1 │ switch (foo) {
    2 │     default:
  > 3 │     case 0:
      │     ^^^^^^^
  > 4 │         break;
      │         ^^^^^^
    5 │     case 1:
    6 │         break;
  
  ℹ because the default clause is present:
  
    1 │ switch (foo) {
  > 2 │     default:
      │     ^^^^^^^^
    3 │     case 0:
    4 │         break;
  
  ℹ Unsafe fix: Remove the useless case.
  
    1 1 │   switch (foo) {
    2   │ - ····default:
    3   │ - ····case·0:
      2 │ + ····default:
    4 3 │           break;
    5 4 │       case 1:

Valid

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switch (foo) {
2
    case 0:
3
        break;
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    default:
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        break;
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}

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switch (foo) {
2
    case 0:
3
        break;
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}