no-unused-labels

Disallow unused labels

Labels that are declared and not used anywhere in the code are most likely an error due to incomplete refactoring.

OUTER_LOOP:
for (const student of students) {
    if (checkScores(student.scores)) {
        continue;
    }
    doSomething(student);
}
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In this case, probably removing OUTER_LOOP: had been forgotten. Such labels take up space in the code and can lead to confusion by readers.

Rule Details

This rule is aimed at eliminating unused labels.

Problems reported by this rule can be fixed automatically, except when there are any comments between the label and the following statement, or when removing a label would cause the following statement to become a directive such as "use strict".

Examples of incorrect code for this rule:

/*eslint no-unused-labels: "error"*/

A: var foo = 0;

B: {
    foo();
}

C:
for (let i = 0; i < 10; ++i) {
    foo();
}
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Examples of correct code for this rule:

/*eslint no-unused-labels: "error"*/

A: {
    if (foo()) {
        break A;
    }
    bar();
}

B:
for (let i = 0; i < 10; ++i) {
    if (foo()) {
        break B;
    }
    bar();
}
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When Not To Use It

If you don’t want to be notified about unused labels, then it’s safe to disable this rule.

Related Rules

• no-extra-label
• no-labels
• no-label-var

Version

This rule was introduced in ESLint v2.0.0-rc.0.

Resources

• Rule source
• Tests source