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• 描述
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

@@unscopable symbol property contains property names that were not included in the ECMAScript standard prior to the ES2015 version. These properties are excluded from with statement bindings.

描述

The default array properties that are excluded from with bindings are:

• copyWithin()
• entries()
• fill()
• find()
• findIndex()
• includes()
• keys()
• values()

见 Symbol.unscopables for how to set unscopables for your own objects.

特性属性在 Array.prototype[@@unscopables]
可写	no
可枚举	no
可配置	yes

范例

Use in with environments

The following code works fine in ES5 and below. However, in ECMAScript 2015 and later, the Array.prototype.keys() method was introduced. That means that inside with environments, "keys" would now be the method and not the variable. This is where now the built-in @@unscopables Array.prototype[@@unscopables] symbol property comes into play and prevents that some of the Array methods are being scoped into the with 语句。

var keys = [];
with (Array.prototype) {
  keys.push('something');
}
Object.keys(Array.prototype[Symbol.unscopables]);
// ["copyWithin", "entries", "fill", "find", "findIndex",
//  "includes", "keys", "values"]
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Array.prototype[@@unscopables]' in that specification.

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
@@unscopables	Chrome 38	Edge 12	Firefox 48	IE No	Opera 25	Safari 10	WebView Android 38	Chrome Android 38	Firefox Android 48	Opera Android 25	Safari iOS 10	Samsung Internet Android 3.0	nodejs 0.12

图例

完整支持

完整支持

不支持

不支持

另请参阅

• Symbol.unscopables

元数据

• 最后修改： May 21, 2020

相关话题

1. 标准内置对象
2. Array
3. 特性
   1. Array.prototype.length
   2. Array.prototype[@@unscopables]
4. 方法
   1. Array.from()
   2. Array.isArray()
   3. Array.of()
   4. Array.prototype.concat()
   5. Array.prototype.copyWithin()
   6. Array.prototype.entries()
   7. Array.prototype.every()
   8. Array.prototype.fill()
   9. Array.prototype.filter()
   10. Array.prototype.find()
   11. Array.prototype.findIndex()
   12. Array.prototype.flat()
   13. Array.prototype.flatMap()
   14. Array.prototype.forEach()
   15. Array.prototype.includes()
   16. Array.prototype.indexOf()
   17. Array.prototype.join()
   18. Array.prototype.keys()
   19. Array.prototype.lastIndexOf()
   20. Array.prototype.map()
   21. Array.prototype.pop()
   22. Array.prototype.push()
   23. Array.prototype.reduce()
   24. Array.prototype.reduceRight()
   25. Array.prototype.reverse()
   26. Array.prototype.shift()
   27. Array.prototype.slice()
   28. Array.prototype.some()
   29. Array.prototype.sort()
   30. Array.prototype.splice()
   31. Array.prototype.toLocaleString()
   32. Array.prototype.toSource()
   33. Array.prototype.toString()
   34. Array.prototype.unshift()
   35. Array.prototype.values()
   36. Array.prototype[@@iterator]()
   37. get Array[@@species]
5. 继承：
6. Function
7. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
8. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
9. Object
10. 特性
    1. Object.prototype.__proto__
    2. Object.prototype.constructor
11. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()