JavaScript中的物件複製(Object Clone)
阿新 • • 發佈:2019-01-11
JavaScript中並沒有直接提供物件複製(Object Clone)的方法。因此下面的程式碼中改變物件b的時候,也就改變了物件a。
a = {k1:1, k2:2, k3:3};
b = a;
b.k2 = 4;
如果只想改變b而保持a不變,就需要對物件a進行復制。
用jQuery進行物件複製
在可以使用jQuery的情況下,jQuery自帶的extend
方法可以用來實現物件的複製。
a = {k1:1, k2:2, k3:3};
b = {};
$.extend(b,a);
var obj1 = { apple: 0, banana: {weight: 52, price: 100}, cherry: 97 }; var obj3; obj3 = $.extend(true, obj1, obj3); console.log(obj1 === obj3);//true obj3.apple = 3; console.log(obj1 === obj3);//true obj3 = $.extend(true, {}, obj1); console.log(obj1 === obj3);//false
Keep in mind that the target object (first argument) will be modified, and will also be returned from $.extend()
. If, however, you want to preserve both of the original objects, you can do so by passing an empty object as the target:
1 |
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方法物件不需要複製也不會存在引用的問題
if(requestObj.error){ errorCallback = requestObj.error; } // console.log(requestObj.error === errorCallback);//true requestObj.error = function(req, msg, err){ console.log(requestObj.url); console.log(req); console.log(msg); console.log(err); if(errorCallback){ // console.log(requestObj.error === errorCallback);//false errorCallback(req, msg, err); } if(dialogConfirm.dialog( "isOpen" )){ dialogConfirm.dialog('close'); } $('#confirmMsg').text(err); $('.confirm-buttons').hide(); $('#btnOk').show(); dialogConfirm.dialog('open'); $('#btnOk').unbind('click'); $('#btnOk').on('click', function() { dialogConfirm.dialog('close'); return false; }); } // console.log(requestObj.error === errorCallback);//false
自定義clone()方法來實現物件複製
下面的方法,是物件複製的基本想法。
Object.prototype.clone = function() {
var copy = (this instanceof Array) ? [] : {};
for (attr in this) {
if (!obj.hasOwnProperty(attr)) continue;
copy[attr] = (typeof this[i] == "object")?obj[attr].clone():obj[attr];
}
return copy;
};
a = {k1:1, k2:2, k3:3};
b = a.clone();
下面的例子則考慮的更全面些,適用於大部分物件的深度複製(Deep Copy)。
function clone(obj) {
// Handle the 3 simple types, and null or undefined
if (null == obj || "object" != typeof obj) return obj;
// Handle Date
if (obj instanceof Date) {
var copy = new Date();
copy.setTime(obj.getTime());
return copy;
}
// Handle Array
if (obj instanceof Array) {
var copy = [];
for (var i = 0, var len = obj.length; i < len; ++i) {
copy[i] = clone(obj[i]);
}
return copy;
}
// Handle Object
if (obj instanceof Object) {
var copy = {};
for (var attr in obj) {
if (obj.hasOwnProperty(attr)) copy[attr] = clone(obj[attr]);
}
return copy;
}
throw new Error("Unable to copy obj! Its type isn't supported.");
}