javascript不用new关键字创建对象示例

<!doctype html>
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<head>
    <meta charset="utf-8">
    <title>无标题文档</title>
    <script language="JavaScript">
<!--
 
        function P(name) {
            if (!(this instanceof P))
                return new P(name);
            //return new P(arguments);
            //var _this = this === window ? {} : this;
            var _this = this;
            _this.name = name;
        }
 
        P.prototype.show = function () {
            alert(this.name + ‘_‘ + this.T);
        }
 
        P.prototype.T = ‘6‘
 
        var a = new P(‘a‘);
        a.show();
        var b = P(‘b‘);
        b.show();
 
        a.show();
 
 
//-->
    </script>
</head>
 
<body>
</body>
</html>