在此页

• 句法
• 描述
• Polyfill
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

Object.is() 方法确定 2 个值是否为 相同值 .

句法

Object.is(value1, value2);
					

参数

value1

要比较的第 1 个值。

value2

要比较的第 2 个值。

返回值

布尔 指示 2 个自变量是否为相同值。

描述

Object.is() 确定 2 个值是否为 相同值 . Two values are the same if one of the following holds:

• both undefined
• both null
• both true or both false
• both strings of the same length with the same characters in the same order
• both the same object (means both object have same reference)
• both numbers and
  • both +0
  • both -0
  • both NaN
  • or both non-zero and both not NaN and both have the same value

This is not the same as being equal according to the == operator. The == operator applies various coercions to both sides (if they are not the same Type) before testing for equality (resulting in such behavior as "" == false being true ), but Object.is doesn't coerce either value.

This is also not the same as being equal according to the === operator. The === operator (and the == operator as well) treats the number values -0 and +0 as equal and treats Number.NaN as not equal to NaN .

Polyfill

if (!Object.is) {
  Object.is = function(x, y) {
    // SameValue algorithm
    if (x === y) { // Steps 1-5, 7-10
      // Steps 6.b-6.e: +0 != -0
      return x !== 0 || 1 / x === 1 / y;
    } else {
      // Step 6.a: NaN == NaN
      return x !== x && y !== y;
    }
  };
}
					

范例

使用 Object.is

Object.is('foo', 'foo');     // true
Object.is(window, window);   // true
Object.is('foo', 'bar');     // false
Object.is([], []);           // false
var foo = { a: 1 };
var bar = { a: 1 };
Object.is(foo, foo);         // true
Object.is(foo, bar);         // false
Object.is(null, null);       // true
// Special Cases
Object.is(0, -0);            // false
Object.is(-0, -0);           // true
Object.is(NaN, 0/0);         // true
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Object.is' in that specification.

浏览器兼容性

The compatibility table on 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
is	Chrome 30	Edge 12	Firefox 22	IE No	Opera 17	Safari 9	WebView Android ≤37	Chrome Android 30	Firefox Android 22	Opera Android 18	Safari iOS 9	Samsung Internet Android 2.0	nodejs 0.10

图例

完整支持

完整支持

不支持

不支持

另请参阅

• 相等比较和相同 — 所有 3 内置相同设施的比较

元数据

• 最后修改： May 20, 2020

相关话题

1. 标准内置对象
2. Object
3. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
4. 方法
   1. Object.assign()
   2. Object.create()
   3. Object.defineProperties()
   4. Object.defineProperty()
   5. Object.entries()
   6. Object.freeze()
   7. Object.fromEntries()
   8. Object.getOwnPropertyDescriptor()
   9. Object.getOwnPropertyDescriptors()
   10. Object.getOwnPropertyNames()
   11. Object.getOwnPropertySymbols()
   12. Object.getPrototypeOf()
   13. Object.is()
   14. Object.isExtensible()
   15. Object.isFrozen()
   16. Object.isSealed()
   17. Object.keys()
   18. Object.preventExtensions()
   19. Object.prototype.__defineGetter__()
   20. Object.prototype.__defineSetter__()
   21. Object.prototype.__lookupGetter__()
   22. Object.prototype.__lookupSetter__()
   23. Object.prototype.hasOwnProperty()
   24. Object.prototype.isPrototypeOf()
   25. Object.prototype.propertyIsEnumerable()
   26. Object.prototype.toLocaleString()
   27. Object.prototype.toSource()
   28. Object.prototype.toString()
   29. Object.prototype.valueOf()
   30. Object.seal()
   31. Object.setPrototypeOf()
   32. Object.values()
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()