eslint/docs/src/rules/no-extra-strict.md

   1 ---
   2 title: no-extra-strict
   3 layout: doc
   4
   5 further_reading:
   6 - https://es5.github.io/#C
   7 ---
   8
   9 Disallows strict mode directives when already in strict mode.
  10
  11 (removed) This rule was **removed** in ESLint v1.0 and **replaced** by the [strict](strict) rule. The `"global"` or `"function"` options in the new rule are similar to the removed rule.
  12
  13 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.
  14
  15 ```js
  16 "use strict";
  17
  18 (function () {
  19     "use strict";
  20     var foo = true;
  21 }());
  22 ```
  23
  24 ## Rule Details
  25
  26 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.
  27
  28 Example of **incorrect** code for this rule:
  29
  30 ::: incorrect
  31
  32 ```js
  33 "use strict";
  34
  35 (function () {
  36     "use strict";
  37     var foo = true;
  38 }());
  39 ```
  40
  41 :::
  42
  43 Examples of **correct** code for this rule:
  44
  45 ::: correct
  46
  47 ```js
  48 "use strict";
  49
  50 (function () {
  51     var foo = true;
  52 }());
  53 ```
  54
  55 :::
  56
  57 ::: correct
  58
  59 ```js
  60 (function () {
  61     "use strict";
  62     var foo = true;
  63 }());
  64 ```
  65
  66 :::