在JavaScript中深度克隆对象最有效的方法是什么？
克隆JavaScript对象最有效的方法是什么？我见过obj=evalunevalo；正在使用，但是。我做过类似于obj=JSON.parseJSON.stringifyo；但质疑效率。我还看到了具有各种缺陷的递归复制函数。在JavaScript中深度克隆对象最有效的方法是什么？,javascript,object,clone,Javascript,Object,Clone,克隆JavaScript对象最有效的方法是什么？我见过obj=evalunevalo；正在使用，但是。我做过类似于obj=JSON.parseJSON.stringifyo；但质疑效率。我还看到了具有各种缺陷的递归复制函数。 我很惊讶没有标准解决方案存在。如果没有任何内置解决方案，您可以尝试： function clone(obj) { if (obj === null || typeof (obj) !== 'object' || 'isActiveClone' in obj)
我很惊讶没有标准解决方案存在。如果没有任何内置解决方案，您可以尝试：
function clone(obj) {
if (obj === null || typeof (obj) !== 'object' || 'isActiveClone' in obj)
return obj;
if (obj instanceof Date)
var temp = new obj.constructor(); //or new Date(obj);
else
var temp = obj.constructor();
for (var key in obj) {
if (Object.prototype.hasOwnProperty.call(obj, key)) {
obj['isActiveClone'] = null;
temp[key] = clone(obj[key]);
delete obj['isActiveClone'];
}
}
return temp;
}
这就是我正在使用的：
function cloneObject(obj) {
var clone = {};
for(var i in obj) {
if(typeof(obj[i])=="object" && obj[i] != null)
clone[i] = cloneObject(obj[i]);
else
clone[i] = obj[i];
}
return clone;
}
Crockford建议，我更喜欢使用此函数：
function object(o) {
function F() {}
F.prototype = o;
return new F();
}
var newObject = object(oldObject);
var newObject = Object.create(oldObject);
对于类似阵列的对象，似乎还没有理想的深度克隆操作符。正如下面的代码所示，John Resig的jQuery克隆器将具有非数字属性的数组转换为非数组的对象，而RegDwight的JSON克隆器则删除非数字属性。以下测试在多个浏览器上演示了这些要点：
function jQueryClone(obj) {
return jQuery.extend(true, {}, obj)
}
function JSONClone(obj) {
return JSON.parse(JSON.stringify(obj))
}
var arrayLikeObj = [[1, "a", "b"], [2, "b", "a"]];
arrayLikeObj.names = ["m", "n", "o"];
var JSONCopy = JSONClone(arrayLikeObj);
var jQueryCopy = jQueryClone(arrayLikeObj);
alert("Is arrayLikeObj an array instance?" + (arrayLikeObj instanceof Array) +
"\nIs the jQueryClone an array instance? " + (jQueryCopy instanceof Array) +
"\nWhat are the arrayLikeObj names? " + arrayLikeObj.names +
"\nAnd what are the JSONClone names? " + JSONCopy.names)
if (!Object.assign) {
Object.defineProperty(Object, 'assign', {
enumerable: false,
configurable: true,
writable: true,
value: function(target) {
'use strict';
if (target === undefined || target === null) {
throw new TypeError('Cannot convert first argument to object');
}
var to = Object(target);
for (var i = 1; i < arguments.length; i++) {
var nextSource = arguments[i];
if (nextSource === undefined || nextSource === null) {
continue;
}
nextSource = Object(nextSource);
var keysArray = Object.keys(nextSource);
for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
var nextKey = keysArray[nextIndex];
var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
if (desc !== undefined && desc.enumerable) {
to[nextKey] = nextSource[nextKey];
}
}
}
return to;
}
});
}
假设对象中只有变量而没有函数，则可以使用：
var newObject = JSON.parse(JSON.stringify(oldObject));
JSON.parse(JSON.stringify(obj))
var clonedObject = {
knownProp: obj.knownProp,
..
}
Object.assign({}, obj);
这通常不是最有效的解决方案，但它满足了我的需要。下面是简单的测试用例
function clone(obj, clones) {
// Makes a deep copy of 'obj'. Handles cyclic structures by
// tracking cloned obj's in the 'clones' parameter. Functions
// are included, but not cloned. Functions members are cloned.
var new_obj,
already_cloned,
t = typeof obj,
i = 0,
l,
pair;
clones = clones || [];
if (obj === null) {
return obj;
}
if (t === "object" || t === "function") {
// check to see if we've already cloned obj
for (i = 0, l = clones.length; i < l; i++) {
pair = clones[i];
if (pair[0] === obj) {
already_cloned = pair[1];
break;
}
}
if (already_cloned) {
return already_cloned;
} else {
if (t === "object") { // create new object
new_obj = new obj.constructor();
} else { // Just use functions as is
new_obj = obj;
}
clones.push([obj, new_obj]); // keep track of objects we've cloned
for (key in obj) { // clone object members
if (obj.hasOwnProperty(key)) {
new_obj[key] = clone(obj[key], clones);
}
}
}
}
return new_obj || obj;
}
f = new Function
f.a = a
ff = clone(f)
ff === f //=> true
ff.a === a //=> false
我知道这是一个老帖子，但我想这可能会对下一个跌跌撞撞的人有所帮助 只要不将对象指定给任何对象，它就不会在内存中保持引用。因此，要创建一个要在其他对象之间共享的对象，必须创建如下工厂：
var a = function(){
return {
father:'zacharias'
};
},
b = a(),
c = a();
c.father = 'johndoe';
alert(b.father);
这里有一个全面的克隆方法，可以克隆任何JavaScript对象。它处理几乎所有的情况：
function clone(src, deep) {
var toString = Object.prototype.toString;
if (!src && typeof src != "object") {
// Any non-object (Boolean, String, Number), null, undefined, NaN
return src;
}
// Honor native/custom clone methods
if (src.clone && toString.call(src.clone) == "[object Function]") {
return src.clone(deep);
}
// DOM elements
if (src.nodeType && toString.call(src.cloneNode) == "[object Function]") {
return src.cloneNode(deep);
}
// Date
if (toString.call(src) == "[object Date]") {
return new Date(src.getTime());
}
// RegExp
if (toString.call(src) == "[object RegExp]") {
return new RegExp(src);
}
// Function
if (toString.call(src) == "[object Function]") {
//Wrap in another method to make sure == is not true;
//Note: Huge performance issue due to closures, comment this :)
return (function(){
src.apply(this, arguments);
});
}
var ret, index;
//Array
if (toString.call(src) == "[object Array]") {
//[].slice(0) would soft clone
ret = src.slice();
if (deep) {
index = ret.length;
while (index--) {
ret[index] = clone(ret[index], true);
}
}
}
//Object
else {
ret = src.constructor ? new src.constructor() : {};
for (var prop in src) {
ret[prop] = deep
? clone(src[prop], true)
: src[prop];
}
}
return ret;
};
npm install clone
var clone = require('clone');
var a = { foo: { bar: 'baz' } }; // inital value of a
var b = clone(a); // clone a -> b
a.foo.bar = 'foo'; // change a
console.log(a); // { foo: { bar: 'foo' } }
console.log(b); // { foo: { bar: 'baz' } }
免责声明：我是该库的作者。这里有一个版本的ConroyP的答案，即使构造函数具有所需的参数，它仍然有效：
//If Object.create isn't already defined, we just do the simple shim,
//without the second argument, since that's all we need here
var object_create = Object.create;
if (typeof object_create !== 'function') {
object_create = function(o) {
function F() {}
F.prototype = o;
return new F();
};
}
function deepCopy(obj) {
if(obj == null || typeof(obj) !== 'object'){
return obj;
}
//make sure the returned object has the same prototype as the original
var ret = object_create(obj.constructor.prototype);
for(var key in obj){
ret[key] = deepCopy(obj[key]);
}
return ret;
}
/**
* Deep copy an object (make copies of all its object properties, sub-properties, etc.)
* An improved version of http://keithdevens.com/weblog/archive/2007/Jun/07/javascript.clone
* that doesn't break if the constructor has required parameters
*
* It also borrows some code from http://stackoverflow.com/a/11621004/560114
*/
function deepCopy(src, /* INTERNAL */ _visited, _copiesVisited) {
if(src === null || typeof(src) !== 'object'){
return src;
}
//Honor native/custom clone methods
if(typeof src.clone == 'function'){
return src.clone(true);
}
//Special cases:
//Date
if(src instanceof Date){
return new Date(src.getTime());
}
//RegExp
if(src instanceof RegExp){
return new RegExp(src);
}
//DOM Element
if(src.nodeType && typeof src.cloneNode == 'function'){
return src.cloneNode(true);
}
// Initialize the visited objects arrays if needed.
// This is used to detect cyclic references.
if (_visited === undefined){
_visited = [];
_copiesVisited = [];
}
// Check if this object has already been visited
var i, len = _visited.length;
for (i = 0; i < len; i++) {
// If so, get the copy we already made
if (src === _visited[i]) {
return _copiesVisited[i];
}
}
//Array
if (Object.prototype.toString.call(src) == '[object Array]') {
//[].slice() by itself would soft clone
var ret = src.slice();
//add it to the visited array
_visited.push(src);
_copiesVisited.push(ret);
var i = ret.length;
while (i--) {
ret[i] = deepCopy(ret[i], _visited, _copiesVisited);
}
return ret;
}
//If we've reached here, we have a regular object
//make sure the returned object has the same prototype as the original
var proto = (Object.getPrototypeOf ? Object.getPrototypeOf(src): src.__proto__);
if (!proto) {
proto = src.constructor.prototype; //this line would probably only be reached by very old browsers
}
var dest = object_create(proto);
//add this object to the visited array
_visited.push(src);
_copiesVisited.push(dest);
for (var key in src) {
//Note: this does NOT preserve ES5 property attributes like 'writable', 'enumerable', etc.
//For an example of how this could be modified to do so, see the singleMixin() function
dest[key] = deepCopy(src[key], _visited, _copiesVisited);
}
return dest;
}
//If Object.create isn't already defined, we just do the simple shim,
//without the second argument, since that's all we need here
var object_create = Object.create;
if (typeof object_create !== 'function') {
object_create = function(o) {
function F() {}
F.prototype = o;
return new F();
};
}
我有两个很好的答案，这取决于您的目标是否是克隆一个普通的老JavaScript对象 我们还假设您的目的是创建一个完整的克隆，而不返回对源对象的原型引用。如果您对完整的克隆不感兴趣，那么您可以使用Crockford模式中的其他一些答案中提供的许多Object.clone例程 对于普通的旧JavaScript对象，在现代运行时克隆对象的一种行之有效的好方法非常简单：
var clone = JSON.parse(JSON.stringify(obj));
var arr1 = ['a', 'b', 'c'];
var arr2 = arr1;
arr1 = ['a', 'b', 'c'];
function copy(o) {
var out, v, key;
out = Array.isArray(o) ? [] : {};
for (key in o) {
v = o[key];
out[key] = (typeof v === "object" && v !== null) ? copy(v) : v;
}
return out;
}
copy(arr1);
$.extend(true, [], arr1); // Jquery Extend
JSON.parse(arr1);
_.cloneDeep(arr1); // Lo-dash
var arr1 = ['a', 'b', 'c'];
var arr2 = arr1;
arr1 = ['a', 'b', 'c'];
下面创建同一对象的两个实例。我找到了它，目前正在使用它。它简单易用
var objToCreate = JSON.parse(JSON.stringify(cloneThis));
对于希望使用JSON.parseJSON.stringifyobj版本但不丢失日期对象的用户，可以使用将字符串转换回日期： 功能克隆{ var regExp=/^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{3}Z$/； 返回JSON.parseJSON.stringifyobj，functionk，v{ 如果typeof v==='string'&®Exp.testv 返回新日期 返回v； } } //用法： 原始变量={ a:[1，null，未定义，0，{a:null}，新日期]， b:{ c{返回0} } } 克隆变量=克隆原始变量 console.logcloned在一行代码中不深度克隆对象的有效方法 方法是ECMAScript 2015 ES6标准的一部分，完全满足您的需要
var clone = Object.assign({}, obj);
function jQueryClone(obj) {
return jQuery.extend(true, {}, obj)
}
function JSONClone(obj) {
return JSON.parse(JSON.stringify(obj))
}
var arrayLikeObj = [[1, "a", "b"], [2, "b", "a"]];
arrayLikeObj.names = ["m", "n", "o"];
var JSONCopy = JSONClone(arrayLikeObj);
var jQueryCopy = jQueryClone(arrayLikeObj);
alert("Is arrayLikeObj an array instance?" + (arrayLikeObj instanceof Array) +
"\nIs the jQueryClone an array instance? " + (jQueryCopy instanceof Array) +
"\nWhat are the arrayLikeObj names? " + arrayLikeObj.names +
"\nAnd what are the JSONClone names? " + JSONCopy.names)
if (!Object.assign) {
Object.defineProperty(Object, 'assign', {
enumerable: false,
configurable: true,
writable: true,
value: function(target) {
'use strict';
if (target === undefined || target === null) {
throw new TypeError('Cannot convert first argument to object');
}
var to = Object(target);
for (var i = 1; i < arguments.length; i++) {
var nextSource = arguments[i];
if (nextSource === undefined || nextSource === null) {
continue;
}
nextSource = Object(nextSource);
var keysArray = Object.keys(nextSource);
for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
var nextKey = keysArray[nextIndex];
var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
if (desc !== undefined && desc.enumerable) {
to[nextKey] = nextSource[nextKey];
}
}
}
return to;
}
});
}
var newObject = angular.copy(oldObject);
var obj = {a:1, b:2, c:3, d:4};
希望这些帮助…我回答这个问题已经晚了，但我有另一种克隆对象的方法：
function cloneObject(obj) {
if (obj === null || typeof(obj) !== 'object')
return obj;
var temp = obj.constructor(); // changed
for (var key in obj) {
if (Object.prototype.hasOwnProperty.call(obj, key)) {
obj['isActiveClone'] = null;
temp[key] = cloneObject(obj[key]);
delete obj['isActiveClone'];
}
}
return temp;
}
var b = cloneObject({"a":1,"b":2}); // calling
var a = {"a":1,"b":2};
var b = JSON.parse(JSON.stringify(a));
Eval不是邪恶的。使用eval很糟糕。如果你害怕它的副作用，那你就用错了。你担心的副作用是使用它的原因。顺便问一下，有人真的回答了你的问题吗？克隆对象是一件棘手的事情，特别是对于任意集合的自定义对象。这可能是为什么没有现成的方法来做。评估通常是个坏主意，因为。在代码中使用eval可能会导致性能下降。注意，JSON方法可能会丢失任何在JSON中没有等价物的Javascript类型。例如：JSON.parseJSON.stringify{a:null，b:NaN，c:Infinity，d:undefined，e:function{}，f:Number，g:false}将生成{a:null，b:null，c:null，g:false}这太错误了！作为在Firefox中实现pushState的人，我对这种黑客行为感到既自豪又厌恶。干得好，伙计们。pushState或Notification hack不适用于某些对象类型，例如Function@ShishirArora你说得对，我刚试过，它抛出了一个“未捕获的DomeException:对象无法克隆”。这对于通知黑客也是如此。它将原语转换为包装器对象，在大多数情况下，这不是一个好的解决方案。@DanubianSailor-我不认为它是……它似乎从一开始就返回原语，而且似乎没有对它们做任何事情，在它们返回时将它们转换为包装器对象。这不是递归复制，因此不能真正解决克隆对象的问题。虽然我测试了一些和u.extend{}，obj是目前最快的：例如，它比JSON.parse快20倍，比Object.assign快60%。它可以很好地复制所有子对象。@mwhite克隆和深度克隆之间有区别。这个答案实际上是克隆，但不是深度克隆。问题是关于递归拷贝。Object.assign，以及给定的自定义赋值，不要递归复制，或者它的使用方式可能与jQiery extend相同：angular.extend{}，obj@Galvani：应该注意jQuery.extend和angular.extend都是浅拷贝。angular.copy是一个深度复制。这很有趣，但当我运行您的测试时，它实际上告诉我方法1是最慢的一个和我一样，块1是最低的！唯一对我有效的解决方案！必须深度克隆包含具有函数属性的其他对象的对象。很好。为什么要将obj['isActiveClone']=null，然后将其删除？你为什么不叫obj.hasOwnPropertykey？嘿，你的最后一个例子错了。在我看来，对于错误的示例，必须使用_clone而不是_cloneDeep。这创建了方法2。对数组不起作用，对吗？方法
2容易受到原型污染，类似于lodash的DefaultsDep。如果i=='''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''！变量A={b:[{A:[1,2,3]，b:[4,5,6]，c:[7,8,9]}；B=Object.assign{}，A；删除B.B[0].B；它还将修改对象A@Gabriel Hautclocq这是因为A.b或b.b都引用内存中的同一对象。如果属性具有非对象值（如数字或字符串），则会正常复制该属性。但是，当复制包含对象值的属性时，它是通过引用而不是通过值进行复制的。另外，请记住数组是JS中的一个对象。证明：typeof[]=='object'&&[]instanceofArray@Unicornist是的，这就是为什么Object.assign没有回答以下问题：在JavaScript中深度克隆对象的最有效方法是什么？。因此，至少不应该将其作为ES6解决方案用于深度克隆。ES6的标题是误导性的，至少应该加以修改，以反映这不是一种深度克隆方法。这个浅薄的词很容易被忽略，很多人只是采用他们在堆栈溢出中找到的最简单的解决方案，而没有阅读所有内容。依赖Object.assign进行对象克隆是危险的。因此我的评论。我使用了一个名为really fast deep clone:的库，对我来说效果非常好。如果您遇到第一条评论中的问题，也将进行浅层复制，您需要启用选项proto:true，对象有属性，而不是变量-函数和日期也不完全是100%克隆注意，您的工作台中有两个错误：首先，它将一些浅克隆lodash u.clone和Object.assign与一些深克隆JSON.parseJSON.stringify进行比较。第二，它说lodash的深度克隆，但它改为浅层克隆；不为我工作。但是Object.assign{}，a做了。更糟糕的是，尝试让o={}；o、 o=o；克隆BJECTO；我不知道这个处理循环结构感谢jQuery，太好了！
var arr1 = ['a', 'b', 'c']; // Becomes arr1 = ['a', 'b', 'c']
var arr2a = arr1.slice(0); // Becomes arr2a = ['a', 'b', 'c'] - deep copy
var arr2b = arr1.concat(); // Becomes arr2b = ['a', 'b', 'c'] - deep copy
var arr1 = [{object:'a'}, {object:'b'}];
function copy(o) {
var out, v, key;
out = Array.isArray(o) ? [] : {};
for (key in o) {
v = o[key];
out[key] = (typeof v === "object" && v !== null) ? copy(v) : v;
}
return out;
}
copy(arr1);
$.extend(true, [], arr1); // Jquery Extend
JSON.parse(arr1);
_.cloneDeep(arr1); // Lo-dash
var objToCreate = JSON.parse(JSON.stringify(cloneThis));
function clone(target, source){
for(let key in source){
// Use getOwnPropertyDescriptor instead of source[key] to prevent from trigering setter/getter.
let descriptor = Object.getOwnPropertyDescriptor(source, key);
if(descriptor.value instanceof String){
target[key] = new String(descriptor.value);
}
else if(descriptor.value instanceof Array){
target[key] = clone([], descriptor.value);
}
else if(descriptor.value instanceof Object){
let prototype = Reflect.getPrototypeOf(descriptor.value);
let cloneObject = clone({}, descriptor.value);
Reflect.setPrototypeOf(cloneObject, prototype);
target[key] = cloneObject;
}
else {
Object.defineProperty(target, key, descriptor);
}
}
let prototype = Reflect.getPrototypeOf(source);
Reflect.setPrototypeOf(target, prototype);
return target;
}
var clone = Object.assign({}, obj);
if (!Object.assign) {
Object.defineProperty(Object, 'assign', {
enumerable: false,
configurable: true,
writable: true,
value: function(target) {
'use strict';
if (target === undefined || target === null) {
throw new TypeError('Cannot convert first argument to object');
}
var to = Object(target);
for (var i = 1; i < arguments.length; i++) {
var nextSource = arguments[i];
if (nextSource === undefined || nextSource === null) {
continue;
}
nextSource = Object(nextSource);
var keysArray = Object.keys(nextSource);
for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
var nextKey = keysArray[nextIndex];
var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
if (desc !== undefined && desc.enumerable) {
to[nextKey] = nextSource[nextKey];
}
}
}
return to;
}
});
}
var newObject = angular.copy(oldObject);
var obj = {a:1, b:2, c:3, d:4};
function deepCopyObj(obj) {
if (null == obj || "object" != typeof obj) return obj;
if (obj instanceof Date) {
var copy = new Date();
copy.setTime(obj.getTime());
return copy;
}
if (obj instanceof Array) {
var copy = [];
for (var i = 0, len = obj.length; i < len; i++) {
copy[i] = deepCopyObj(obj[i]);
}
return copy;
}
if (obj instanceof Object) {
var copy = {};
for (var attr in obj) {
if (obj.hasOwnProperty(attr)) copy[attr] = deepCopyObj(obj[attr]);
}
return copy;
}
throw new Error("Unable to copy obj this object.");
}
var deepCopyObj = JSON.parse(JSON.stringify(obj));
var deepCopyObj = angular.copy(obj);
var deepCopyObj = jQuery.extend(true, {}, obj);
var deepCopyObj = _.cloneDeep(obj); //latest version UndescoreJs makes shallow copy
function cloneObject(obj) {
if (obj === null || typeof(obj) !== 'object')
return obj;
var temp = obj.constructor(); // changed
for (var key in obj) {
if (Object.prototype.hasOwnProperty.call(obj, key)) {
obj['isActiveClone'] = null;
temp[key] = cloneObject(obj[key]);
delete obj['isActiveClone'];
}
}
return temp;
}
var b = cloneObject({"a":1,"b":2}); // calling
var a = {"a":1,"b":2};
var b = JSON.parse(JSON.stringify(a));
var a = {"a":1,"b":2};
// Deep copy
var newObject = jQuery.extend(true, {}, a);
var obj = {
a: 1,
b: {
c: 2
}
}
var newObj = JSON.parse(JSON.stringify(obj));
obj.b.c = 20;
console.log(obj); // { a: 1, b: { c: 20 } }
console.log(newObj); // { a: 1, b: { c: 2 } }
function cloneObject(obj) {
var clone = {};
for(var i in obj) {
if(obj[i] != null && typeof(obj[i])=="object")
clone[i] = cloneObject(obj[i]);
else
clone[i] = obj[i];
}
return clone;
}
var obj = {
a: 1,
b: {
c: 2
}
}
var newObj = cloneObject(obj);
obj.b.c = 20;
console.log(obj); // { a: 1, b: { c: 20 } }
console.log(newObj); // { a: 1, b: { c: 2 } }
var obj = {
a: 1,
b: {
c: 2
}
}
var newObj = _.cloneDeep(obj);
obj.b.c = 20;
console.log(obj); // { a: 1, b: { c: 20 } }
console.log(newObj); // { a: 1, b: { c: 2 } }
var obj = {
a: 1,
b: 2
}
var newObj = _.clone(obj);
obj.b = 20;
console.log(obj); // { a: 1, b: 20 }
console.log(newObj); // { a: 1, b: 2 }
var obj = {
a: 1,
b: {
c: 2
}
}
var newObj = Object.assign({}, obj);
obj.b.c = 20;
console.log(obj); // { a: 1, b: { c: 20 } }
console.log(newObj); // { a: 1, b: { c: 20 } } --> WRONG
// Note: Properties on the prototype chain and non-enumerable properties cannot be copied.
var obj = {
a: 1,
b: 2
}
var newObj = _.clone(obj);
obj.b = 20;
console.log(obj); // { a: 1, b: 20 }
console.log(newObj); // { a: 1, b: 2 }
var obj = {
a: 1,
b: {
c: 2
}
}
var newObj = _.cloneDeep(obj);
obj.b.c = 20;
console.log(obj); // { a: 1, b: { c: 20 } }
console.log(newObj); // { a: 1, b: { c: 20 } } --> WRONG
// (Create a shallow-copied clone of the provided plain object. Any nested objects or arrays will be copied by reference, not duplicated.)