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JavaScript: Can ECMAScript 5's Strict Mode ("use strict") be enabled using single quotes ('use strict')?

开发者 https://www.devze.com 2023-02-14 23:52 出处:网络
JavaScript doesn\'t care if your Strings are double-quoted \"double\" or single-quoted \'single\'. Every example of ECMAScript 5\'s strict mode has it enabled by \"use strict\" in double-quotes. Can

JavaScript doesn't care if your Strings are double-quoted "double" or single-quoted 'single'.

Every example of ECMAScript 5's strict mode has it enabled by "use strict" in double-quotes. Can I do the following (single-quotes):

开发者_StackOverflowalert(function(){
  'use strict';
  return !this;
}());

This will return true if Strict mode is enabled, and false if it is not.


For you, without using a browser that supports strict mode:

A Use Strict Directive is an ExpressionStatement in a Directive Prologue whose StringLiteral is either the exact character sequences "use strict" or 'use strict'. A Use Strict Directive may not contain an EscapeSequence or LineContinuation.


http://ecma262-5.com/ELS5_HTML.htm#Section_14.1

A Use Strict Directive is an ExpressionStatement in a Directive Prologue whose StringLiteral is either the exact character sequences "use strict" or 'use strict'. A Use Strict Directive may not contain an EscapeSequence or LineContinuation.


According to the mozilla documentation you can use both "use strict"; and 'use strict';.

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