5）构造函数的用法：
例 3.5.1
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8"/>
</head>
<script>
function Student(name, age)
{
/* 马克-to-win：later on we can use it in
var doc = new ActiveXObject( "Microsoft.XMLDOM" );
doc.async="false";
doc.load(str);
when a property has a this, means that this property is a member property.
*/
this.name = name;
this.age = age;
this.parti = function()
{
document.writeln("名字是：" + this.name + "<br>");
document.writeln("年纪是：" + this.age + "<br>");
};
}
var p = new Student('jeri', 3);
document.writeln("typeof p is " + typeof(p));
//typeof(p) is object
p.parti();
p.age = 4;
p.parti();
/*the following two methods can also access some properties.*/
document.writeln("" + p["age"]);
document.writeln("" + p["a" + "ge"]);
if (p instanceof Student) document.writeln("p是Student的实例<br>");
/*javascript 中的对象全部是Object 的子类
Because this object is the topmost parent object in the prototype inheritance hierarchy, all other object classes inherit its methods and properties. It's a close enough call that JavaScript 2.0 may well move it into the class-based object-oriented category at which time the prototype inheritance would be replaced with super-class/sub-class mechanisms and the arguments become null and void. */
/*When the Global object is created, it always has at least the following properties:
Object object
Function object
Array object
String object
Boolean object
Number object
Date object
Math object
Value properties
*/
if (p instanceof Object) document.writeln("p是Object的实例");
</script>
文章转载自：https://blog.csdn.net/qq_44594249/article/details/100032253