什么是最有效的方式来克隆一个JavaScript对象?我已经看到obj = eval(uneval(o));被使用,但它是非标准的,仅支持Firefox.我做了事情,如obj = JSON.parse(JSON.stringify(o));但质疑效率。
当前回答
代码:
// extends 'from' object with members from 'to'. If 'to' is null, a deep clone of 'from' is returned
function extend(from, to)
{
if (from == null || typeof from != "object") return from;
if (from.constructor != Object && from.constructor != Array) return from;
if (from.constructor == Date || from.constructor == RegExp || from.constructor == Function ||
from.constructor == String || from.constructor == Number || from.constructor == Boolean)
return new from.constructor(from);
to = to || new from.constructor();
for (var name in from)
{
to[name] = typeof to[name] == "undefined" ? extend(from[name], null) : to[name];
}
return to;
}
测试:
var obj =
{
date: new Date(),
func: function(q) { return 1 + q; },
num: 123,
text: "asdasd",
array: [1, "asd"],
regex: new RegExp(/aaa/i),
subobj:
{
num: 234,
text: "asdsaD"
}
}
var clone = extend(obj);
其他回答
Shallow copy one-lineer (ECMAScript 第五版):
var origin = { foo : {} };
var copy = Object.keys(origin).reduce(function(c,k){c[k]=origin[k];return c;},{});
console.log(origin, copy);
console.log(origin == copy); // false
console.log(origin.foo == copy.foo); // true
并下载单线复制(ECMAScript 第六版,2015年):
var origin = { foo : {} };
var copy = Object.assign({}, origin);
console.log(origin, copy);
console.log(origin == copy); // false
console.log(origin.foo == copy.foo); // true
如果沒有任何內建一個,你可以嘗試:
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;
}
假设您只拥有属性,而不是对象中的任何功能,您只能使用:
var newObject = JSON.parse(JSON.stringify(oldObject));
class Handler { static deepCopy (obj) { if (Object.prototype.toString.call(obj) === '[object Array]') { const result = []; for (let i = 0, len = obj.length; i < len; i++) { result[i] = Handler.deepCopy(obj[i]); } return result; } else if (Object.prototype.toString.call(obj) === '[object Object]') { const result = {}; for (let prop in obj) { result[prop] = Handler.deepCopy(obj[prop]); } return result; } return obj; } }
我认为这是最好的解决方案,如果你想通用你的对象克隆算法,它可以用与或没有jQuery,虽然我建议你放弃jQuery的扩展方法,如果你想你克隆的对象有相同的“类”与原始一个。
function clone(obj){
if(typeof(obj) == 'function')//it's a simple function
return obj;
//of it's not an object (but could be an array...even if in javascript arrays are objects)
if(typeof(obj) != 'object' || obj.constructor.toString().indexOf('Array')!=-1)
if(JSON != undefined)//if we have the JSON obj
try{
return JSON.parse(JSON.stringify(obj));
}catch(err){
return JSON.parse('"'+JSON.stringify(obj)+'"');
}
else
try{
return eval(uneval(obj));
}catch(err){
return eval('"'+uneval(obj)+'"');
}
// I used to rely on jQuery for this, but the "extend" function returns
//an object similar to the one cloned,
//but that was not an instance (instanceof) of the cloned class
/*
if(jQuery != undefined)//if we use the jQuery plugin
return jQuery.extend(true,{},obj);
else//we recursivley clone the object
*/
return (function _clone(obj){
if(obj == null || typeof(obj) != 'object')
return obj;
function temp () {};
temp.prototype = obj;
var F = new temp;
for(var key in obj)
F[key] = clone(obj[key]);
return F;
})(obj);
}