noUselessSwitchCase

Diagnostic Category: lint/complexity/noUselessSwitchCase

JavaScript (and super languages)

Since: v1.0.0

Sources:

Same as: unicorn/no-useless-switch-case

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

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

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

  ✖ 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;

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

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

  ✖ 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

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

switch (foo) {
    case 0:
        break;
}

How to configure

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