javascript当中静态方法和prototype用法

6)静态方法和prototype(难)

例 3.6.1

<head>
    <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
</head>
<script>
    /*note that 马克-to-win: static variable's value has nothing to do with instance's variable's value.instance 名称 can not 直接access static member like in java.
This is different from Java,比如下面例子中,Student.number=2,但是d1.number就为undefined.This is different from Java,但在实例方法中(比如d1.info)可以访问Student.number。这是和java中一样的。或者说function外或任何地方都可以访问Student.number。反过来,d1.age也可以在静态方法中访问,就像在function外一样,任何地方都能访问d1.age。String.prototype.abcd,这是给所有的实例加属性而不是静态属性。*/
    function Student(number, agev)
    {
        this.age = agev;
        /*static variable's value can not be accessed by instance */
        Student.number = number;
        /*lb is local variable, but not a member variable because it is not modified by this. from outside it can not be accessed. refer to noblockScope.html */
        var lb = 0;
    }
    var d1 = new Student(1, 3);
    document.writeln("this的age属性为means window.age" + this.age + "<br>");
    document.writeln("d1的age属性为" + d1.age + "<br>");
    document.writeln("d1的number属性为" + d1.number + "<br>");
    document.writeln("通过Student访问静态number属性为" + Student.number + "<br>");
    document.writeln("d1的lb属性为" + d1.lb + "<br><hr>");
    d1.qixy = "abc";/*以随意为实例加属性或方法*/
    document.writeln("可以随意为实例加属性或方法see following,d1的qixy属性为" + d1.qixy + "<br><hr>");
    document.writeln("是否有静态变量qixy" + Student.qixy + "<br><hr>");
    d1.info = function()/*此方法仅为d1对象所用*/
    {
        document.writeln("对象的qixy属性:" + this.qixy);

        document.writeln("对象的age属性:" + this.age);
        /*下列话是合法的, 因为不是this.number, 而是Student.number*/
        document.writeln("static method is " + Student.number);
    };
    Student.prototype.infop = function()/*此方法可以为所有Student对象所用*/
    {
        document.writeln("对象的qixy属性p:" + this.qixy);
        document.writeln("对象的age属性p:" + this.age);

更多内容请见原文,文章转载自:https://blog.csdn.net/qq_44594249/article/details/100053745

posted @ 2020-12-25 15:15  师徒行者  阅读(121)  评论(0编辑  收藏  举报