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使用隐藏的new来创建对象_jquery

WBOY
Release： 2016-05-16 18:08:52
Original
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很多时候我们是这样写类，然后使用new创建对象的。

复制代码 代码如下:

function Person(name,age){
this.name=name;
this.age=age;
}
Person.prototype={
setName : function(n){this.name=n;},
getName : function(){return this.name;}
}
var p = new Person('jack',25);

改成这样的
复制代码 代码如下:

function Person(name,age){
//条件改为(this==window)或(this==self)或(this.constructor!=Object)
if(!this.setName){
return new Person(name,age);
}
this.name=name;
this.age=age;
}
Person.prototype={
setName : function(n){this.name=n;},
getName : function(){return this.name;}
}
var p = Person('jack',25);

注意该类较最上面的写类方式中多了以下
复制代码 代码如下:

if(!this.setName){
return new Person(name,age);
}

好，创建类的实例（对象）方式也变成了如下
复制代码 代码如下:

var p = Person('jack',25);

这种创建方式（函数调用）较上面的少了“new_”，new和空格，实际上是在类内部new了。而这样方式每次创建对象可以减少4个byte。
如果把类内部的if判断条件换成非prototype上的属性，如this.name。程序会提示出错：too much recursion
复制代码 代码如下:

function Person(name,age){
if(!this.name){
return new Person(name,age);
}
this.name=name;
this.age=age;
}
Person.prototype={
setName : function(n){this.name=n;},
getName : function(){return this.name;}
}
var p = Person('jack',25);
Related labels：
new Create object
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