no-extra-strict

当已经处于严格模式时，不允许使用严格模式指令。

¥Disallows strict mode directives when already in strict mode.

"use strict"; 指令适用于它出现的范围以及该范围内包含的所有内部范围。因此，在这些内部范围之一中使用 "use strict"; 指令是不必要的。

¥The "use strict"; directive applies to the scope in which it appears and all inner scopes contained within that scope. Therefore, using the "use strict"; directive in one of these inner scopes is unnecessary.

"use strict";

(function () {
    "use strict";
    var foo = true;
}());
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规则详情

¥Rule Details

该规则旨在防止不必要的 "use strict"; 指令。因此，它会在已经处于严格模式时遇到 "use strict"; 指令时触发警告。

¥This rule is aimed at preventing unnecessary "use strict"; directives. As such, it will warn when it encounters a "use strict"; directive when already in strict mode.

此规则的错误代码示例：

¥Example of incorrect code for this rule:

"use strict";

(function () {
    "use strict";
    var foo = true;
}());
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此规则的正确代码示例：

¥Examples of correct code for this rule:

"use strict";

(function () {
    var foo = true;
}());
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(function () {
    "use strict";
    var foo = true;
}());
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版本

此规则是在 ESLint v0.3.0 中引入，并在 v1.0.0-rc-1 中删除。

进阶读物

Annotated ES5
es5.github.io