我需要能够在运行时合并两个（非常简单的）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
有没有内置的方法可以做到这一点？我不需要递归，也不需要合并函数，只需要在平面对象上合并方法。
ECMAScript 2018 标准方法
您将使用对象跨页：
let merged = {...obj1, ...obj2};
merged现在是 和 的并集。中的属性将覆盖 中的属性。obj1obj2obj2obj1
/** 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};
下面也是此语法的 MDN 文档。如果你使用的是 babel，你需要 babel-plugin-transform-object-rest-spread 插件才能工作。
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);
适用于 ES5 及更早版本的方法
for (var attrname in obj2) { obj1[attrname] = obj2[attrname]; }
请注意，如果您仍然想使用未修改的 .，这将简单地添加可能不是您想要的所有属性。obj2obj1obj1
如果你使用的框架在你的原型上到处都是，那么你必须通过像 这样的检查变得更花哨，但该代码将适用于99%的情况。hasOwnProperty
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;
}
jQuery也有一个实用程序：http://api.jquery.com/jQuery.extend/。
摘自 jQuery 文档：
// Merge options object into settings object
var settings = { validate: false, limit: 5, name: "foo" };
var options = { validate: true, name: "bar" };
jQuery.extend(settings, options);
// Now the content of settings object is the following:
// { validate: true, limit: 5, name: "bar" }
上面的代码将改变现有的名为 settings 的对象。
如果要在不修改任一参数的情况下创建新对象，请使用：
var defaults = { validate: false, limit: 5, name: "foo" };
var options = { validate: true, name: "bar" };
/* Merge defaults and options, without modifying defaults */
var settings = $.extend({}, defaults, options);
// The content of settings variable is now the following:
// {validate: true, limit: 5, name: "bar"}
// The 'defaults' and 'options' variables remained the same.
