你应该使用lodash的默认值Deep

_.defaultsDeep({ 'user': { 'name': 'barney' } }, { 'user': { 'name': 'fred', 'age': 36 } });
// → { 'user': { 'name': 'barney', 'age': 36 } }

最好的方法是使用Object.defineProperty添加一个不可枚举的适当属性。

通过这种方式，您仍然可以迭代对象财产，而无需使用Object.prototype.extend创建属性时新创建的“extend”。

希望这有助于：

Object.defineProperty(Object.prototype, "extend", {
    enumerable: false,
    value: function(from) {
        var props = Object.getOwnPropertyNames(from);
        var dest = this;
        props.forEach(function(name) {
            if (name in dest) {
                var destination = Object.getOwnPropertyDescriptor(from, name);
                Object.defineProperty(dest, name, destination);
            }
        });
        return this;
    }
});

一旦你做到了这一点，你就可以做到：

var obj = {
    name: 'stack',
    finish: 'overflow'
}
var replacement = {
    name: 'stock'
};

obj.extend(replacement);

我刚刚在这里写了一篇博文：http://onemoredigit.com/post/1527191998/extending-objects-in-node-js

这是我的刺

支持深度合并不改变参数采用任意数量的参数不扩展对象原型不依赖于其他库（jQuery、MooTools、Undercore.js等）包括检查hasOwnProperty短：）/*递归合并财产并返回新对象对象1&lt；-对象2[&lt；-…]*/函数合并（）{变量dst=｛｝，srcp，args=[].splice.call（参数，0）;while（参数长度>0）{src=参数拼接（0，1）[0]；if（toString.call（src）=='[object object]'）{for（src中的p）{if（src.hasOwnProperty（p））{if（toString.call（src[p]）=='[object object]'）{dst[p]=合并（dst[p]||{}，src[p]）；}其他{dst[p]=src[p]；}}}}}返回dst；}

例子：

a = {
    "p1": "p1a",
    "p2": [
        "a",
        "b",
        "c"
    ],
    "p3": true,
    "p5": null,
    "p6": {
        "p61": "p61a",
        "p62": "p62a",
        "p63": [
            "aa",
            "bb",
            "cc"
        ],
        "p64": {
            "p641": "p641a"
        }
    }
};

b = {
    "p1": "p1b",
    "p2": [
        "d",
        "e",
        "f"
    ],
    "p3": false,
    "p4": true,
    "p6": {
        "p61": "p61b",
        "p64": {
            "p642": "p642b"
        }
    }
};

c = {
    "p1": "p1c",
    "p3": null,
    "p6": {
        "p62": "p62c",
        "p64": {
            "p643": "p641c"
        }
    }
};

d = merge(a, b, c);


/*
    d = {
        "p1": "p1c",
        "p2": [
            "d",
            "e",
            "f"
        ],
        "p3": null,
        "p5": null,
        "p6": {
            "p61": "p61b",
            "p62": "p62c",
            "p63": [
                "aa",
                "bb",
                "cc"
            ],
            "p64": {
                "p641": "p641a",
                "p642": "p642b",
                "p643": "p641c"
            }
        },
        "p4": true
    };
*/

我今天需要合并对象，这个问题（和答案）对我帮助很大。我尝试了一些答案，但没有一个符合我的需要，所以我组合了一些答案并自己添加了一些东西，并提出了一个新的合并函数。这里是：

var merge = function() {
    var obj = {},
        i = 0,
        il = arguments.length,
        key;
    for (; i < il; i++) {
        for (key in arguments[i]) {
            if (arguments[i].hasOwnProperty(key)) {
                obj[key] = arguments[i][key];
            }
        }
    }
    return obj;
};

一些示例用法：

var t1 = {
    key1: 1,
    key2: "test",
    key3: [5, 2, 76, 21]
};
var t2 = {
    key1: {
        ik1: "hello",
        ik2: "world",
        ik3: 3
    }
};
var t3 = {
    key2: 3,
    key3: {
        t1: 1,
        t2: 2,
        t3: {
            a1: 1,
            a2: 3,
            a4: [21, 3, 42, "asd"]
        }
    }
};

console.log(merge(t1, t2));
console.log(merge(t1, t3));
console.log(merge(t2, t3));
console.log(merge(t1, t2, t3));
console.log(merge({}, t1, { key1: 1 }));

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;
}

此解决方案创建一个新对象，并能够处理多个对象。

此外，它是递归的，您可以选择要覆盖值和对象的天气。

    function extendObjects() {

        var newObject        = {};
        var overwriteValues  = false;
        var overwriteObjects = false;

        for ( var indexArgument = 0; indexArgument < arguments.length; indexArgument++ ) {

            if ( typeof arguments[indexArgument] !== 'object' ) {

                if ( arguments[indexArgument] == 'overwriteValues_True' ) {

                    overwriteValues = true;            
                } else if ( arguments[indexArgument] == 'overwriteValues_False' ) {

                    overwriteValues = false;                             
                } else if ( arguments[indexArgument] == 'overwriteObjects_True' ) {

                    overwriteObjects = true;     
                } else if ( arguments[indexArgument] == 'overwriteObjects_False' ) {

                    overwriteObjects = false; 
                }

            } else {

                extendObject( arguments[indexArgument], newObject, overwriteValues, overwriteObjects );
            }

        }

        function extendObject( object, extendedObject, overwriteValues, overwriteObjects ) {

            for ( var indexObject in object ) {

                if ( typeof object[indexObject] === 'object' ) {

                    if ( typeof extendedObject[indexObject] === "undefined" || overwriteObjects ) {
                        extendedObject[indexObject] = object[indexObject];
                    }

                    extendObject( object[indexObject], extendedObject[indexObject], overwriteValues, overwriteObjects );

                } else {

                    if ( typeof extendedObject[indexObject] === "undefined" || overwriteValues ) {
                        extendedObject[indexObject] = object[indexObject];
                    }

                }

            }     

            return extendedObject;

        }

        return newObject;
    }

    var object1           = { a : 1, b : 2, testArr : [888, { innArr : 1 }, 777 ], data : { e : 12, c : { lol : 1 }, rofl : { O : 3 } } };
    var object2           = { a : 6, b : 9, data : { a : 17, b : 18, e : 13, rofl : { O : 99, copter : { mao : 1 } } }, hexa : { tetra : 66 } };
    var object3           = { f : 13, g : 666, a : 333, data : { c : { xD : 45 } }, testArr : [888, { innArr : 3 }, 555 ]  };

    var newExtendedObject = extendObjects( 'overwriteValues_False', 'overwriteObjects_False', object1, object2, object3 );

newExtendedObject的内容：

{"a":1,"b":2,"testArr":[888,{"innArr":1},777],"data":{"e":12,"c":{"lol":1,"xD":45},"rofl":{"O":3,"copter":{"mao":1}},"a":17,"b":18},"hexa":{"tetra":66},"f":13,"g":666}

小提琴：http://jsfiddle.net/o0gb2umb/