Disallow Unused Labels (no-unused-labels)

禁用未使用过的标签 (no-unused-labels)

The "extends": "eslint:recommended" property in a configuration file enables this rule.

配置文件中的 "extends": "eslint:recommended" 属性启用了此规则。

The --fix option on the command line can automatically fix some of the problems reported by this rule.

命令行中的 --fix 选项可以自动修复一些该规则报告的问题。

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

只声明却没有使用的标签可能是由于不完全的重构造成的错误。

OUTER_LOOP:
for (const student of students) {
    if (checkScores(student.scores)) {
        continue;
    }
    doSomething(student);
}

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.

在这个例子中，可能是忘记了移除 OUTER_LOOP: 。这样的标签不仅占据代码空间，而且会使读者感到迷惑。

Rule Details

This rule is aimed at eliminating unused labels.

该规则旨在消除未使用过的标签。

Examples of incorrect code for this rule:

错误 代码示例：

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

A: var foo = 0;

B: {
    foo();
}

C:
for (let i = 0; i < 10; ++i) {
    foo();
}

Examples of correct code for this rule:

正确 代码示例：

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

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

B:
for (let i = 0; i < 10; ++i) {
    if (foo()) {
        break B;
    }
    bar();
}

When Not To Use It

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

如果你不想收到关于未使用的标签的通知，禁用此规则即可。

Version

This rule was introduced in ESLint 2.0.0-rc.0.

该规则在 ESLint 2.0.0-rc.0 中被引入。

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