eslint/docs/rules/no-unused-labels.md

   1 # Disallow Unused Labels (no-unused-labels)
   2
   3 Labels that are declared and not used anywhere in the code are most likely an error due to incomplete refactoring.
   4
   5 ```js
   6 OUTER_LOOP:
   7 for (const student of students) {
   8     if (checkScores(student.scores)) {
   9         continue;
  10     }
  11     doSomething(student);
  12 }
  13 ```
  14
  15 In this case, probably removing `OUTER_LOOP:` had been forgotten.
  16 Such labels take up space in the code and can lead to confusion by readers.
  17
  18 ## Rule Details
  19
  20 This rule is aimed at eliminating unused labels.
  21
  22 Examples of **incorrect** code for this rule:
  23
  24 ```js
  25 /*eslint no-unused-labels: "error"*/
  26
  27 A: var foo = 0;
  28
  29 B: {
  30     foo();
  31 }
  32
  33 C:
  34 for (let i = 0; i < 10; ++i) {
  35     foo();
  36 }
  37 ```
  38
  39 Examples of **correct** code for this rule:
  40
  41 ```js
  42 /*eslint no-unused-labels: "error"*/
  43
  44 A: {
  45     if (foo()) {
  46         break A;
  47     }
  48     bar();
  49 }
  50
  51 B:
  52 for (let i = 0; i < 10; ++i) {
  53     if (foo()) {
  54         break B;
  55     }
  56     bar();
  57 }
  58 ```
  59
  60 ## When Not To Use It
  61
  62 If you don't want to be notified about unused labels, then it's safe to disable this rule.
  63
  64 ## Related Rules
  65
  66 * [no-extra-label](./no-extra-label.md)
  67 * [no-labels](./no-labels.md)
  68 * [no-label-var](./no-label-var.md)