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用jQuery和JavaScript深度复制JSON对象的方法

你有时可能需要复制一个JSON对象,jQuery提供了的extend方法以前是无法进行深度复制的,不过现在也已经支持了:

// Shallow copy var newObject = jQuery.extend({}, oldObject);  // Deep copy var newObject = jQuery.extend(true, {}, oldObject);

StackOverFlow的一位网友提供了一个深度复制的函数

Array.prototype.clone = function(doDeepCopy) {

if(doDeepCopy) {

var encountered = [{

a : this,

b : []

}];

var item,

levels = [{a:this, b:encountered[0].b, i:0}],

level = 0,

i = 0,

len = this.length;

while(i < len) {

item = levels[level].a[i];

if(Object.prototype.toString.call(item) === "[object Array]") {

for(var j = encountered.length - 1; j >= 0; j--) {

if(encountered[j].a === item) {

levels[level].b.push(encountered[j].b);

break;

}

}

if(j < 0) {

encountered.push(j = {

a : item,

b : []

});

levels[level].b.push(j.b);

levels[level].i = i + 1;

levels[++level] = {a:item, b:j.b, i:0};

i = -1;

len = item.length;

}

}

else {

levels[level].b.push(item);

}

if(++i == len && level > 0) {

levels.pop();

i = levels[--level].i;

len = levels[level].a.length;

}

}

return encountered[0].b;

}

else {

return this.slice(0);

}

};

不过此函数是加到Array对象原型上的,这意味着你使用 for in 枚举array数组时也会枚举出这个方法。这里有一个函数版本:

function clone(item) {

if (!item) { return item; } // null, undefined values check

var types = [ Number, String, Boolean ], 

result;

// normalizing primitives if someone did new String('aaa'), or new Number('444');

types.forEach(function(type) {

if (item instanceof type) {

result = type( item );

}

});

if (typeof result == "undefined") {

if (Object.prototype.toString.call( item ) === "[object Array]") {

result = [];

item.forEach(function(child, index, array) { 

result[index] = clone( child );

});

} else if (typeof item == "object") {

// testing that this is DOM

if (item.nodeType && typeof item.cloneNode == "function") {

var result = item.cloneNode( true );    

} else if (!item.prototype) { // check that this is a literal

if (item instanceof Date) {

result = new Date(item);

} else {

// it is an object literal

result = {};

for (var i in item) {

result[i] = clone( item[i] );

}

}

} else {

// depending what you would like here,

// just keep the reference, or create new object

if (false && item.constructor) {

// would not advice to do that, reason? Read below

result = new item.constructor();

} else {

result = item;

}

}

} else {

result = item;

}

}

return result;

}

var copy = clone({

one : {

'one-one' : new String("hello"),

'one-two' : [

"one", "two", true, "four"

]

},

two : document.createElement("div"),

three : [

{

name : "three-one",

number : new Number("100"),

obj : new function() {

this.name = "Object test";

}   

}

]

})

其实深度复制JavaScript对象还有一个更加简单的方法, 一行代码即可,比如:

var cloned = JSON.parse(JSON.stringify(objectToClone));

参考: http://stackoverflow.com/questions/122102/what-is-the-most-efficient-way-to-clone-an-object

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