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);
文章转载自：https://blog.csdn.net/qq_44594249/article/details/100053745
原文地址：https://www.cnblogs.com/renzhe111/p/12179179.html