noUnusedLabels

Diagnostic Category: lint/correctness/noUnusedLabels

JavaScript (and super languages)

Since: v1.0.0

Sources:

Same as: no-unused-labels

Description

Disallow unused labels.

Labels that are declared and never used are most likely an error due to incomplete refactoring.

The rule ignores reactive Svelte statements in Svelte components.

Examples

Invalid

LOOP: for (const x of xs) {
    if (x > 0) {
        break;
    }
    f(x);
}

code-block.js:1:1 lint/correctness/noUnusedLabels  FIXABLE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ Unused label.
  
  > 1 │ LOOP: for (const x of xs) {
      │ ^^^^
    2 │     if (x > 0) {
    3 │         break;
  
  ℹ The label is not used by any break statement and continue statement.
  
  ℹ Safe fix: Remove the unused label.
  
    1 │ LOOP:·for·(const·x·of·xs)·{
      │ ------

Valid

LOOP: for (const x of xs) {
    if (x > 0) {
        break LOOP;
    }
    f(x);
}

function nonNegative(n) {
    DEV: assert(n >= 0);
    return n;
}

<script>
$: { /* reactive block */ }
</script>

How to configure

{
  "linter": {
    "rules": {
      "correctness": {
        "noUnusedLabels": "error"
      }
    }
  }
}