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.entries() method returns an array of a given object's own enumerable string-keyed property [ key , value ] pairs, in the same order as that provided by a for...in loop. (The only important difference is that a for...in loop enumerates properties in the prototype chain as well).

The order of the array returned by Object.entries() does not depend on how an object is defined. If there is a need for certain ordering, then the array should be sorted first, like Object.entries(obj).sort((a, b) => b[0].localeCompare(a[0])); .

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

句法

Object.entries(obj)
					

参数

obj

The object whose own enumerable string-keyed property [ key , value ] pairs are to be returned.

返回值

An array of the given object's own enumerable string-keyed property [ key , value ] pairs.

描述

Object.entries() returns an array whose elements are arrays corresponding to the enumerable string-keyed property [ key , value ] pairs found directly upon object . The ordering of the properties is the same as that given by looping over the property values of the object manually.

Polyfill

To add compatible Object.entries() support in older environments that do not natively support it, you can use any of the following:

• a demonstration implementation of Object.entries 在 tc39/proposal-object-values-entries (if you don't need any support for IE);
• a polyfill in the es-shims/Object.entries repositories;
• or, you can use the simple, ready-to-deploy polyfill listed below:

if (!Object.entries) {
  Object.entries = function( obj ){
    var ownProps = Object.keys( obj ),
        i = ownProps.length,
        resArray = new Array(i); // preallocate the Array
    while (i--)
      resArray[i] = [ownProps[i], obj[ownProps[i]]];
    return resArray;
  };
}
					

For the above polyfill code snippet, if you need support for IE<9, then you will also need an Object.keys() polyfill (such as the one found on the Object.keys page).

范例

const obj = { foo: 'bar', baz: 42 };
console.log(Object.entries(obj)); // [ ['foo', 'bar'], ['baz', 42] ]
// array like object
const obj = { 0: 'a', 1: 'b', 2: 'c' };
console.log(Object.entries(obj)); // [ ['0', 'a'], ['1', 'b'], ['2', 'c'] ]
// array like object with random key ordering
const anObj = { 100: 'a', 2: 'b', 7: 'c' };
console.log(Object.entries(anObj)); // [ ['2', 'b'], ['7', 'c'], ['100', 'a'] ]
// getFoo is property which isn't enumerable
const myObj = Object.create({}, { getFoo: { value() { return this.foo; } } });
myObj.foo = 'bar';
console.log(Object.entries(myObj)); // [ ['foo', 'bar'] ]
// non-object argument will be coerced to an object
console.log(Object.entries('foo')); // [ ['0', 'f'], ['1', 'o'], ['2', 'o'] ]
// returns an empty array for any primitive type, since primitives have no own properties
console.log(Object.entries(100)); // [ ]
// iterate through key-value gracefully
const obj = { a: 5, b: 7, c: 9 };
for (const [key, value] of Object.entries(obj)) {
  console.log(`${key} ${value}`); // "a 5", "b 7", "c 9"
}
// Or, using array extras
Object.entries(obj).forEach(([key, value]) => {
  console.log(`${key} ${value}`); // "a 5", "b 7", "c 9"
});
					

Converting an Object 到 Map

new Map() constructor accepts an iterable of entries . With Object.entries , you can easily convert from Object to Map :

const obj = { foo: 'bar', baz: 42 };
const map = new Map(Object.entries(obj));
console.log(map); // Map { foo: "bar", baz: 42 }
					

Iterating through an Object

使用 Array Destructuring , you can iterate through objects easily.

const obj = { foo: 'bar', baz: 42 };
Object.entries(obj).forEach(([key, value]) => console.log(`${key}: ${value}`)); // "foo: bar", "baz: 42"
					

规范

规范
ECMAScript (ECMA-262) The definition of 'Object.entries' 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
entries	Chrome 54	Edge 14	Firefox 47	IE No	Opera 41	Safari 10.1	WebView Android 54	Chrome Android 54	Firefox Android 47	Opera Android 41	Safari iOS 10.3	Samsung Internet Android 6.0	nodejs 7.0.0 7.0.0 6.5.0 Disabled Disabled From version 6.5.0: this feature is behind the --harmony runtime flag.

图例

完整支持

完整支持

不支持

不支持

用户必须明确启用此特征。

用户必须明确启用此特征。

另请参阅

• Enumerability and ownership of properties
• Object.keys()
• Object.values()
• Object.prototype.propertyIsEnumerable()
• Object.create()
• Object.fromEntries()
• Object.getOwnPropertyNames()
• Map.prototype.entries()
• Map.prototype.keys()
• Map.prototype.values()

元数据

• 最后修改： Jun 7, 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()