我需要能够在运行时合并两个(非常简单)JavaScript对象。例如,我想:

var obj1 = { food: 'pizza', car: 'ford' }
var obj2 = { animal: 'dog' }

obj1.merge(obj2);

//obj1 now has three properties: food, car, and animal

是否有一种内置的方法来实现这一点?我不需要递归,也不需要合并函数,只需要平面对象上的方法。


当前回答

ECMAScript 2018标准方法

您可以使用对象扩散:

let merged = {...obj1, ...obj2};

merged现在是obj1和obj2的并集。obj2中的财产将覆盖obj1中的属性。

/** There's no limit to the number of objects you can merge.
 *  Later properties overwrite earlier properties with the same name. */
const allRules = {...obj1, ...obj2, ...obj3};

这里还有此语法的MDN文档。如果您正在使用babel,则需要@babel/plugin提议对象rest spread插件才能工作(该插件包含在ES2018中的@babel/preset-env中)。

ECMAScript 2015(ES6)标准方法

/* For the case in question, you would do: */
Object.assign(obj1, obj2);

/** There's no limit to the number of objects you can merge.
 *  All objects get merged into the first object. 
 *  Only the object in the first argument is mutated and returned.
 *  Later properties overwrite earlier properties with the same name. */
const allRules = Object.assign({}, obj1, obj2, obj3, etc);

(参见MDN JavaScript参考)


ES5及更早版本的方法

for (var attrname in obj2) { obj1[attrname] = obj2[attrname]; }

请注意,这将简单地将obj2的所有属性添加到obj1中,如果您仍然希望使用未修改的obj1,那么这可能不是您想要的。

如果你使用的是一个在你的原型上到处都是垃圾的框架,那么你必须通过hasOwnProperty这样的检查来获得更高的效率,但这段代码在99%的情况下都是有效的。

示例函数:

/**
 * Overwrites obj1's values with obj2's and adds obj2's if non existent in obj1
 * @param obj1
 * @param obj2
 * @returns obj3 a new object based on obj1 and obj2
 */
function merge_options(obj1,obj2){
    var obj3 = {};
    for (var attrname in obj1) { obj3[attrname] = obj1[attrname]; }
    for (var attrname in obj2) { obj3[attrname] = obj2[attrname]; }
    return obj3;
}

其他回答

您可以简单地使用jQuery扩展

var obj1 = { val1: false, limit: 5, name: "foo" };
var obj2 = { val2: true, name: "bar" };

jQuery.extend(obj1, obj2);

现在obj1包含obj1和obj2的所有值

Harmony ECMAScript 2015(ES6)指定了将执行此操作的Object.assign。

Object.assign(obj1, obj2);

当前的浏览器支持越来越好,但如果您正在为没有支持的浏览器开发,则可以使用polyfill。

在MooTools中,有Object.merge():

Object.merge(obj1, obj2);

对于不太复杂的对象,可以使用JSON:

var obj1 = { food: 'pizza', car: 'ford' }
var obj2 = { animal: 'dog', car: 'chevy'}
var objMerge;

objMerge = JSON.stringify(obj1) + JSON.stringify(obj2);

// {"food": "pizza","car":"ford"}{"animal":"dog","car":"chevy"}

objMerge = objMerge.replace(/\}\{/, ","); //  \_ replace with comma for valid JSON

objMerge = JSON.parse(objMerge); // { food: 'pizza', animal: 'dog', car: 'chevy'}
// Of same keys in both objects, the last object's value is retained_/

请注意,在此示例中,“}{”不能出现在字符串中!

在一行代码中合并N个对象的财产

Object.assign方法是ECMAScript 2015(ES6)标准的一部分,它完全符合您的需要。(不支持IE)

var clone = Object.assign({}, obj);

assign()方法用于将所有可枚举自身财产的值从一个或多个源对象复制到目标对象。

阅读更多。。。

支持旧浏览器的polyfill:

if (!Object.assign) {
  Object.defineProperty(Object, 'assign', {
    enumerable: false,
    configurable: true,
    writable: true,
    value: function(target) {
      'use strict';
      if (target === undefined || target === null) {
        throw new TypeError('Cannot convert first argument to object');
      }

      var to = Object(target);
      for (var i = 1; i < arguments.length; i++) {
        var nextSource = arguments[i];
        if (nextSource === undefined || nextSource === null) {
          continue;
        }
        nextSource = Object(nextSource);

        var keysArray = Object.keys(nextSource);
        for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
          var nextKey = keysArray[nextIndex];
          var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
          if (desc !== undefined && desc.enumerable) {
            to[nextKey] = nextSource[nextKey];
          }
        }
      }
      return to;
    }
  });
}