1.包装对象
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
/*function Aaa(){
this.name = ‘小明‘;
}
Aaa.prototype.showName = function(){
alert( this.name );
};
var a1 = new Aaa();
a1.showName();
var arr = new Array();
arr.push();
arr.sort();
//在JS源码 : 系统对象也是基于原型的程序
function Array(){
this.lenglth = 0;
}
Array.prototype.push = function(){};
Array.prototype.sort = function(){};*/
//尽量不要去修改或者添加系统对象下面的方法和属性
var arr = [1,2,3];
Array.prototype.push = function(){
//this : 1,2,3
//arguments : 4,5,6
for(var i=0;i<arguments.length;i++){
this[this.length] = arguments[i]
}
return this.length;
};
arr.push(4,5,6);
alert( arr );
//pop shift unshift splice sort
</script>
</head>
<body>
</body>
</html>
2.包装对象
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
/*var str = ‘hello‘;
alert( typeof str );
str.charAt(0);
str.indexOf(‘e‘);*/
//null undefined
//包装对象 : 基本类型都有自己对应的包装对象 : String Number Boolean
/*var str = new String(‘hello‘);
//alert( typeof str );
alert(str.charAt(1));
String.prototype.charAt = function(){};*/
//var str = ‘hello‘;
//str.charAt(0); //基本类型会找到对应的包装对象类型，然后包装对象把所有的属性和方法给了基本类型，然后包装对象消失
/*var str = ‘hello‘;
String.prototype.lastValue = function(){
return this.charAt(this.length-1);
};
alert( str.lastValue() ); //o*/
var str = ‘hello‘;
str.number = 10;
alert( str.number ); //undefined
</script>
</head>
<body>
</body>
</html>
3.
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
//原型链 : 实例对象与原型之间的连接，叫做原型链
//原型链的最外层 : Object.prototype
function Aaa(){
//this.num = 20;
}
//Aaa.prototype.num = 10;
Object.prototype.num = 30;
var a1 = new Aaa();
alert(a1.num);
</script>
</head>
<body>
</body>
</html>
4.hasownproperty
<!DOCTYPE HTML> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>无标题文档</title> <script> //hasOwnProperty : 看是不是对象自身下面的属性 var arr = []; arr.num = 10; Array.prototype.num2 = 20; //alert( arr.hasOwnProperty(‘num‘) ); //true alert( arr.hasOwnProperty(‘num2‘) ); //false </script> </head> <body> </body> </html>
5constructor
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
//constructor : 查看对象的构造函数
/*function Aaa(){
}
var a1 = new Aaa();
alert( a1.constructor ); //Aaa
var arr = [];
alert( arr.constructor == Array ); //true*/
/*function Aaa(){
}
//Aaa.prototype.constructor = Aaa; //每一个函数都会有的，都是自动生成的
//Aaa.prototype.constructor = Array;
var a1 = new Aaa();
alert( a1.hasOwnProperty == Object.prototype.hasOwnProperty ); //true*/
/*function Aaa(){
}
Aaa.prototype.name = ‘小明‘;
Aaa.prototype.age = 20;
Aaa.prototype = {
constructor : Aaa,
name : ‘小明‘,
age : 20
};
var a1 = new Aaa();
alert( a1.constructor );*/
function Aaa(){
}
Aaa.prototype.name = 10;
Aaa.prototype.constructor = Aaa;
for( var attr in Aaa.prototype ){
alert(attr);
}
</script>
</head>
<body>
</body>
</html>
6instanceof
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
//instanceof : 对象与构造函数在原型链上是否有关系
function Aaa(){
}
var a1 = new Aaa();
//alert( a1 instanceof Object ); //true
var arr = [];
alert( arr instanceof Array );
</script>
</head>
<body>
</body>
</html>
7.tostring
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
//toString() : 系统对象下面都是自带的 , 自己写的对象都是通过原型链找object下面的
/*var arr = [];
alert( arr.toString == Object.prototype.toString ); //false*/
/*function Aaa(){
}
var a1 = new Aaa();
alert( a1.toString == Object.prototype.toString ); //true*/
//toString() : 把对象转成字符串
/*var arr = [1,2,3];
Array.prototype.toString = function(){
return this.join(‘+‘);
};
alert( arr.toString() ); //‘1,2,3‘*/
//var num = 255;
//alert( num.toString(16) ); //‘ff‘
//利用toString做类型的判断 :
/*var arr = [];
alert( Object.prototype.toString.call(arr) == ‘[object Array]‘ ); */ //‘[object Array]‘
window.onload = function(){
var oF = document.createElement(‘iframe‘);
document.body.appendChild( oF );
var ifArray = window.frames[0].Array;
var arr = new ifArray();
//alert( arr.constructor == Array ); //false
//alert( arr instanceof Array ); //false
alert( Object.prototype.toString.call(arr) == ‘[object Array]‘ ); //true
};
</script>
</head>
<body>
</body>
</html>
8.继承
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
//继承 : 子类不影响父类，子类可以继承父类的一些功能 ( 代码复用 )
//属性的继承 : 调用父类的构造函数 call
//方法的继承 : for in : 拷贝继承 (jquery也是采用拷贝继承extend)
function CreatePerson(name,sex){ //父类
this.name = name;
this.sex = sex;
}
CreatePerson.prototype.showName = function(){
alert( this.name );
};
var p1 = new CreatePerson(‘小明‘,‘男‘);
//p1.showName();
function CreateStar(name,sex,job){ //子类
CreatePerson.call(this,name,sex);
this.job = job;
}
//CreateStar.prototype = CreatePerson.prototype;
extend( CreateStar.prototype , CreatePerson.prototype );
CreateStar.prototype.showJob = function(){
};
var p2 = new CreateStar(‘黄晓明‘,‘男‘,‘演员‘);
p2.showName();
function extend(obj1,obj2){
for(var attr in obj2){
obj1[attr] = obj2[attr];
}
}
</script>
</head>
<body>
</body>
</html>
9.9对象的复制
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<script>
/*var a = {
name : ‘小明‘
};
var b = a;
b.name = ‘小强‘;
alert( a.name );*/
/*var a = {
name : ‘小明‘
};
//var b = a;
var b = {};
extend( b , a );
b.name = ‘小强‘;
alert( a.name );
function extend(obj1,obj2){
for(var attr in obj2){
obj1[attr] = obj2[attr];
}
}*/
var a = [1,2,3];
var b = a;
//b.push(4);
b = [1,2,3,4];
alert(a);
</script>
</head>
<body>
</body>
</html>
时间： 2024-10-06 20:26:10