我扩展了David Coallier的方法：

增加了合并多个对象的可能性支持深层对象override参数（如果最后一个参数是布尔值，则检测到）

如果覆盖为false，则不会覆盖任何属性，但会添加新的财产。

用法：obj.merge（合并…[，覆盖]）；

这是我的代码：

Object.defineProperty(Object.prototype, "merge", {
    enumerable: false,
    value: function () {
        var override = true,
            dest = this,
            len = arguments.length,
            props, merge, i, from;

        if (typeof(arguments[arguments.length - 1]) === "boolean") {
            override = arguments[arguments.length - 1];
            len = arguments.length - 1;
        }

        for (i = 0; i < len; i++) {
            from = arguments[i];
            if (from != null) {
                Object.getOwnPropertyNames(from).forEach(function (name) {
                    var descriptor;

                    // nesting
                    if ((typeof(dest[name]) === "object" || typeof(dest[name]) === "undefined")
                            && typeof(from[name]) === "object") {

                        // ensure proper types (Array rsp Object)
                        if (typeof(dest[name]) === "undefined") {
                            dest[name] = Array.isArray(from[name]) ? [] : {};
                        }
                        if (override) {
                            if (!Array.isArray(dest[name]) && Array.isArray(from[name])) {
                                dest[name] = [];
                            }
                            else if (Array.isArray(dest[name]) && !Array.isArray(from[name])) {
                                dest[name] = {};
                            }
                        }
                        dest[name].merge(from[name], override);
                    } 

                    // flat properties
                    else if ((name in dest && override) || !(name in dest)) {
                        descriptor = Object.getOwnPropertyDescriptor(from, name);
                        if (descriptor.configurable) {
                            Object.defineProperty(dest, name, descriptor);
                        }
                    }
                });
            }
        }
        return this;
    }
});

示例和测试用例：

function clone (obj) {
    return JSON.parse(JSON.stringify(obj));
}
var obj = {
    name : "trick",
    value : "value"
};

var mergeObj = {
    name : "truck",
    value2 : "value2"
};

var mergeObj2 = {
    name : "track",
    value : "mergeObj2",
    value2 : "value2-mergeObj2",
    value3 : "value3"
};

assertTrue("Standard", clone(obj).merge(mergeObj).equals({
    name : "truck",
    value : "value",
    value2 : "value2"
}));

assertTrue("Standard no Override", clone(obj).merge(mergeObj, false).equals({
    name : "trick",
    value : "value",
    value2 : "value2"
}));

assertTrue("Multiple", clone(obj).merge(mergeObj, mergeObj2).equals({
    name : "track",
    value : "mergeObj2",
    value2 : "value2-mergeObj2",
    value3 : "value3"
}));

assertTrue("Multiple no Override", clone(obj).merge(mergeObj, mergeObj2, false).equals({
    name : "trick",
    value : "value",
    value2 : "value2",
    value3 : "value3"
}));

var deep = {
    first : {
        name : "trick",
        val : "value"
    },
    second : {
        foo : "bar"
    }
};

var deepMerge = {
    first : {
        name : "track",
        anotherVal : "wohoo"
    },
    second : {
        foo : "baz",
        bar : "bam"
    },
    v : "on first layer"
};

assertTrue("Deep merges", clone(deep).merge(deepMerge).equals({
    first : {
        name : "track",
        val : "value",
        anotherVal : "wohoo"
    },
    second : {
        foo : "baz",
        bar : "bam"
    },
    v : "on first layer"
}));

assertTrue("Deep merges no override", clone(deep).merge(deepMerge, false).equals({
    first : {
        name : "trick",
        val : "value",
        anotherVal : "wohoo"
    },
    second : {
        foo : "bar",
        bar : "bam"
    },
    v : "on first layer"
}));

var obj1 = {a: 1, b: "hello"};
obj1.merge({c: 3});
assertTrue(obj1.equals({a: 1, b: "hello", c: 3}));

obj1.merge({a: 2, b: "mom", d: "new property"}, false);
assertTrue(obj1.equals({a: 1, b: "hello", c: 3, d: "new property"}));

var obj2 = {};
obj2.merge({a: 1}, {b: 2}, {a: 3});
assertTrue(obj2.equals({a: 3, b: 2}));

var a = [];
var b = [1, [2, 3], 4];
a.merge(b);
assertEquals(1, a[0]);
assertEquals([2, 3], a[1]);
assertEquals(4, a[2]);


var o1 = {};
var o2 = {a: 1, b: {c: 2}};
var o3 = {d: 3};
o1.merge(o2, o3);
assertTrue(o1.equals({a: 1, b: {c: 2}, d: 3}));
o1.b.c = 99;
assertTrue(o2.equals({a: 1, b: {c: 2}}));

// checking types with arrays and objects
var bo;
a = [];
bo = [1, {0:2, 1:3}, 4];
b = [1, [2, 3], 4];

a.merge(b);
assertTrue("Array stays Array?", Array.isArray(a[1]));

a = [];
a.merge(bo);
assertTrue("Object stays Object?", !Array.isArray(a[1]));

a = [];
a.merge(b);
a.merge(bo);
assertTrue("Object overrides Array", !Array.isArray(a[1]));

a = [];
a.merge(b);
a.merge(bo, false);
assertTrue("Object does not override Array", Array.isArray(a[1]));

a = [];
a.merge(bo);
a.merge(b);
assertTrue("Array overrides Object", Array.isArray(a[1]));

a = [];
a.merge(bo);
a.merge(b, false);
assertTrue("Array does not override Object", !Array.isArray(a[1]));

我的equals方法可以在这里找到：JavaScript中的对象比较

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

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

使用jQuery.exde（）-Link

// Merge obj1 & obj2 to result
var result1 = $.extend( {}, obj1, obj2 );

使用_.merge（）-链接

// Merge obj1 & obj2 to result
var result2 = _.merge( {}, obj1, obj2 );

使用_.exde（）-链接

// Merge obj1 & obj2 to result
var result3 = _.extend( {}, obj1, obj2 );

使用Object.assign（）ECMAScript 2015（ES6）-Link

// Merge obj1 & obj2 to result
var result4 = Object.assign( {}, obj1, obj2 );

全部输出

obj1: { animal: 'dog' }
obj2: { food: 'pizza', car: 'ford' }
result1: {food: "pizza", car: "ford", animal: "dog"}
result2: {food: "pizza", car: "ford", animal: "dog"}
result3: {food: "pizza", car: "ford", animal: "dog"}
result4: {food: "pizza", car: "ford", animal: "dog"}

jQuery还有一个实用程序：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setting的对象。

如果要在不修改任何参数的情况下创建新对象，请使用以下命令：

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.

在Ext JS 4中，可以如下所示：

var mergedObject = Ext.Object.merge(object1, object2)

// Or shorter:
var mergedObject2 = Ext.merge(object1, object2)

请参见合并（对象）：对象。

这会将obj合并为“默认”def。obj优先于两者中存在的任何对象，因为obj被复制到def中。还要注意，这是递归的。

function mergeObjs(def, obj) {
    if (typeof obj == 'undefined') {
        return def;
    } else if (typeof def == 'undefined') {
        return obj;
    }
    for (var i in obj) {
        if (obj[i] != null && obj[i].constructor == Object) {
            def[i] = mergeObjs(def[i], obj[i]);
        } else {
            def[i] = obj[i];
        }
    }
    return def;
}

a = {x : {y : [123]}}
b = {x : {z : 123}}
console.log(mergeObjs(a, b));
// {x: {y : [123], z : 123}}

gossi对David Coallier方法的扩展：

检查这两行：

from = arguments[i];
Object.getOwnPropertyNames(from).forEach(function (name) {

需要针对空对象检查“from”。。。例如，如果合并以前在服务器上创建的来自Ajax响应的对象，则对象属性的值可以为“null”，在这种情况下，上述代码会生成一个错误消息：

“from”不是有效对象

因此，例如，将“…Object.getOwnPropertyNames（from）.forEach…”函数包装为“if（from！=null）｛…｝”将防止发生该错误。