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

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/

基于Markus和vsync的回答，这是一个扩展版本。该函数接受任意数量的参数。它可以用于设置DOM节点上的财产，并对值进行深度复制。然而，第一个论点是通过引用给出的。

要检测DOM节点，使用isDOMNode（）函数（请参阅堆栈溢出问题JavaScript isDOM-如何检查JavaScript对象是否为DOM对象？）

它在Opera 11、Firefox 6、Internet Explorer 8和Google Chrome 16中进行了测试。

Code

function mergeRecursive() {

  // _mergeRecursive does the actual job with two arguments.
  var _mergeRecursive = function (dst, src) {
    if (isDOMNode(src) || typeof src !== 'object' || src === null) {
      return dst;
    }

    for (var p in src) {
      if (!src.hasOwnProperty(p))
        continue;
      if (src[p] === undefined)
        continue;
      if ( typeof src[p] !== 'object' || src[p] === null) {
        dst[p] = src[p];
      } else if (typeof dst[p]!=='object' || dst[p] === null) {
        dst[p] = _mergeRecursive(src[p].constructor===Array ? [] : {}, src[p]);
      } else {
        _mergeRecursive(dst[p], src[p]);
      }
    }
    return dst;
  }

  // Loop through arguments and merge them into the first argument.
  var out = arguments[0];
  if (typeof out !== 'object' || out === null)
    return out;
  for (var i = 1, il = arguments.length; i < il; i++) {
    _mergeRecursive(out, arguments[i]);
  }
  return out;
}

一些示例

设置HTML元素的innerHTML和样式

mergeRecursive(
  document.getElementById('mydiv'),
  {style: {border: '5px solid green', color: 'red'}},
  {innerHTML: 'Hello world!'});

合并数组和对象。请注意，undefined可用于保存左侧数组/对象中的值。

o = mergeRecursive({a:'a'}, [1,2,3], [undefined, null, [30,31]], {a:undefined, b:'b'});
// o = {0:1, 1:null, 2:[30,31], a:'a', b:'b'}

任何非JavaScript对象的参数（包括null）都将被忽略。除了第一个参数之外，也会丢弃DOM节点。注意，像new String（）这样创建的字符串实际上是对象。

o = mergeRecursive({a:'a'}, 1, true, null, undefined, [1,2,3], 'bc', new String('de'));
// o = {0:'d', 1:'e', 2:3, a:'a'}

如果要将两个对象合并为一个新对象（不影响其中任何一个），请提供｛｝作为第一个参数

var a={}, b={b:'abc'}, c={c:'cde'}, o;
o = mergeRecursive(a, b, c);
// o===a is true, o===b is false, o===c is false

编辑（由收割者很快）：

还要合并阵列

function mergeRecursive(obj1, obj2) {
  if (Array.isArray(obj2)) { return obj1.concat(obj2); }
  for (var p in obj2) {
    try {
      // Property in destination object set; update its value.
      if ( obj2[p].constructor==Object ) {
        obj1[p] = mergeRecursive(obj1[p], obj2[p]);
      } else if (Array.isArray(obj2[p])) {
        obj1[p] = obj1[p].concat(obj2[p]);
      } else {
        obj1[p] = obj2[p];
      }
    } catch(e) {
      // Property in destination object not set; create it and set its value.
      obj1[p] = obj2[p];
    }
  }
  return obj1;
}

您可以为每个对象分配一个默认的合并（也许“继承”一个更好的名称）方法：

它应该使用对象或实例化函数。

如果需要，下面的代码处理重写合并值：

Object.prototype.merge = function(obj, override) {
// Don't override by default

    for (var key in obj) {
        var n = obj[key];
        var t = this[key];
        this[key] = (override && t) ? n : t;
    };

};

测试数据如下：

var Mammal = function () {
    this.eyes = 2;
    this.thinking_brain = false;
    this.say = function () {
    console.log('screaming like a mammal')};
}

var Human = function () {
    this.thinking_brain = true;
    this.say = function() {console.log('shouting like a human')};
}

john = new Human();

// Extend mammal, but do not override from mammal
john.merge(new Mammal());
john.say();

// Extend mammal and override from mammal
john.merge(new Mammal(), true);
john.say();

ES2018/TypeScript：很多答案都可以，但当您需要合并两个对象而不覆盖重叠的对象键时，我已经找到了一个更优雅的解决方案。

我的函数还接受无限数量的对象作为函数参数进行合并：

（这里我使用的是TypeScript表示法，如果您使用的是纯JavaScript，请随意删除函数参数中的：object[]类型）。

const merge = (...objects: object[]) => {
  return objects.reduce((prev, next) => {
    Object.keys(prev).forEach(key => {
      next[key] = { ...next[key], ...prev[key] }
    })
    return next
  })
}

我使用纯JavaScript中的以下内容。它从最右边的参数开始，并将它们组合到第一个参数。没有返回值，只修改了第一个参数，最左边的参数（第一个除外）在财产上具有最高的权重。

var merge = function() {
  var il = arguments.length;

  for (var i = il - 1; i > 0; --i) {
    for (var key in arguments[i]) {
      if (arguments[i].hasOwnProperty(key)) {
        arguments[0][key] = arguments[i][key];
      }
    }
  }
};