javascript當中靜態方法和prototype用法

時間 2020-01-13

標籤 javascript 當中靜態方法 prototype 用法欄目 JavaScript 简体版

原文原文鏈接

6）靜態方法和prototype（難）

例 3.6.1

<head>
 <meta http-equiv="content-type" content="text/html; charset=utf-8"/>
</head>
<script>
 /*note that 馬克-to-win： static variable's value has nothing to do with instance's variable's value.instance 名稱 can not 直接access static member like in java.
This is different from Java，好比下面例子中，Student.number=2,可是d1.number就爲undefined.This is different from Java，但在實例方法中（好比d1.info）能夠訪問Student.number。這是和java中同樣的。或者說function外或任何地方均可以訪問Student.number。反過來，d1.age也能夠在靜態方法中訪問，就像在function外同樣，任何地方都能訪問d1.age。String.prototype.abcd，這是給全部的實例加屬性而不是靜態屬性。*/
 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屬性爲means window.age" + this.age + " ");
 document.writeln("d1的age屬性爲" + d1.age + " ");
 document.writeln("d1的number屬性爲" + d1.number + " ");
 document.writeln("經過Student訪問靜態number屬性爲" + Student.number + " ");
 document.writeln("d1的lb屬性爲" + d1.lb + " <hr>");
 d1.qixy = "abc";/*以隨意爲實例加屬性或方法*/
 document.writeln("能夠隨意爲實例加屬性或方法see following，d1的qixy屬性爲" + d1.qixy + " <hr>");
 document.writeln("是否有靜態變量qixy" + Student.qixy + " <hr>");
 d1.info = function()/*此方法僅爲d1對象所用*/
 {
 document.writeln("對象的qixy屬性:" + this.qixy);

 document.writeln("對象的age屬性:" + this.age);
 /*下列話是合法的，由於不是this.number，而是Student.number*/
 document.writeln("static method is " + Student.number);
 };
 Student.prototype.infop = function()/*此方法能夠爲全部Student對象所用*/
 {
 document.writeln("對象的qixy屬性p:" + this.qixy);
 document.writeln("對象的age屬性p:" + this.age);html