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  • jquery--new返回值

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <script type=text/javascript charset=utf-8>
    
    function F(){
        this.name = 1;
        this.sc = 4;
        alert(2);
        return function(){
            this.age = 2;
            this.name = 3;
            alert(1);
        }
    }
    var f = new F();
    alert(typeof f);//function
    alert(f.name);//输出函数的名字
    alert(f.age);//undefined
    alert(f.sc);//undefined        
    
    function G(){
        this.name = 1;
        this.sc = 4;
        return {
            name : 14,
            age : 15
        };
    }
    var g =new G();
    alert(typeof g);//object
    alert(g.name);//14
    alert(g.age);//15
    alert(g.sc);//undefined
    
    function H(){
        this.name = 1;
        this.sc = 4;
    }
    var g =new H();
    alert(typeof g);//object
    alert(g.name);//1
    
    function H(){
        this.name = 1;
        this.sc = 4;
        return this;
    }
    var g =new H();
    alert(typeof g);//object
    alert(g.name);//1        
    alert(g.sc);//4      
    
    function L(){
        this.name = 1;
        this.sc = 4;
        return new Array(1,2,3);
    }
    var l =new L();
    alert(typeof l);//object
    alert(l);//1,2,3
    alert(l.name);//undefined
    alert(l.sc);//undefined  
    
    function E(){
        this.name = 1;
        this.sc = 4;
        return 'ssss';//return的是引用类型new函数就返回return的引用类型对象,基本类型就还是返回函数类的实例对象。
    }
    var e =new E();
    alert(typeof e);//object
    alert(e);//object
    alert(e.charAt(1));//e.charAt is not a function
    alert(e.name);//1
    alert(e.sc);//4
    </script>
    </head>
    <body>
    </body>
    </html>
    function F(){
        this.n = 1;
        this.sc = 4;
        return function FF(){
            this.n = 11;
            this.sc = 44;
            return function FFF(){
                this.n = 111;
                this.sc = 442;                    
    
            }
        }
    }
    var f = new F();
    alert(typeof f);
    alert(f.name);//FF, new F(),函数F值执行他的那层执行一遍
    alert(f.n)//undefined   
    
    
    function F(a){
        this.n = 1;
        this.sc = 4;
        return new init(a);   //new init(),如果init类没有return引用就返回init类的对象,否则返回init类中return的引用对象
    }
    
    function init(){
        this.n = 11;
        return {n:arguments[0]}
    }
    
    var d = F(3);
    alert(d.n);//3      
    
    
    
    function F(a){
        this.n = 1;
        this.sc = 4;
        return new init(a);
    }
    
    function init(){
        this.n = 11;
        return 44
    }
    
    var d = F(3);
    alert(d.n);//11

     new F() 不一定返回F类的对象,有可能返回F()函数里面返回的对象。

    function F(a){
        this.n = 1;
        this.sc = 4;
        return new G(a); //不一定返回G对象,返回{}
    }
    
    function G(){
        this.n = 11;
        return {n:arguments[0]}
    }
    
    var d =new F(3); //不一定返回F的对象,返回的是F函数里面的new G()这个G的对象
    alert(d.n);//3   
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  • 原文地址:https://www.cnblogs.com/yaowen/p/6898711.html
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