小编典典

如何动态合并两个 JavaScript 对象的属性?

javascript

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

有没有内置的方法来做到这一点?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。


阅读 93

收藏
2022-01-24

共1个答案

小编典典

ECMAScript 2018 标准方法

您将使用对象传播

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

merged现在是 和 的obj1并集obj2。中的属性obj2将覆盖obj1.

/** 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};

这里也是这个语法的MDN 文档。如果你使用 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);

(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,如果您仍想使用未修改obj2的.obj1``obj1

如果你使用的框架在你的原型上都是废话,那么你必须通过类似的检查来获得更好的体验hasOwnProperty,但该代码将适用于 99% 的情况。

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;
}
2022-01-24