JavaScript-DOM续
一.路由的跳转
<body>
<a href="#/course">课程</a>
<a href="#/main">首页</a>
<div class="show"></div>
<script>
//window.inhashchange是一个用来检测路由是否变化的函数
window.onhashchange=function(){
//location.hash是获取路由的最后一部分
switch (location.hash) {
case '#/course' :
document.getElementsByClassName('show')[0].innerHTML='我是课程';
break;
case '#/main' :
document.getElementsByClassName('show')[0].innerHTML='我是首页';
break;
default:
break;
}
}
</script>
</body>
二.tab栏选项卡
(1)
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
*{
padding: 0;
margin: 0;
}
li{
float: left;
}
ul{
list-style: none;
}
a{
display: inline-block;
height: 50px;
width: 100px;
line-height: 50px;
text-align: center;
text-decoration: none;
}
.clearfix:after{
content: '.';
clear: both;
display: block;
visibility: hidden;
height: 0;
}
p{
height: 200px;
width: 300px;
background-color: red;
line-height: 200px;
text-align: center;
display: none;
}
.active{
display: block;
}
</style>
</head>
<body>
<div>
<ul class="clearfix">
<li>
<a href="#">首页</a>
</li>
<li>
<a href="#">新闻</a>
</li>
<li>
<a href="#">图片</a>
</li>
<p >首页内容</p>
<p>新闻内容</p>
<p>图片内容</p>
</ul>
<script>
oA=document.getElementsByTagName('a');
//此处的var i=0相当于在最上面的全局变量中var i,此处是i=0
for(var i=0;i<oA.length;i++){
oA[i].index = i;//把i找一个地方存储起来
oA[i].onclick=function (){
for(var j=0;j<oA.length;j++){
oP=document.getElementsByTagName('p');
oP[j].className='';
oA[j].style.backgroundColor='#a5a6b0';
}
oA[this.index].style.backgroundColor='red';
oP[this.index].className='active';
}
}
</script>
</div>
</body>
//作用域:一个{}代表一个作用域
//变量提升:见上面代码
(2)用let解决变量提升问题(用let不会产生变量提升的现象)
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
*{
padding: 0;
margin: 0;
}
li{
float: left;
}
ul{
list-style: none;
}
a{
display: inline-block;
height: 50px;
width: 100px;
background-color: #a5a6b0;
line-height: 50px;
text-align: center;
text-decoration: none;
}
.clearfix:after{
content: '.';
clear: both;
display: block;
visibility: hidden;
height: 0;
}
p{
height: 200px;
width: 300px;
background-color: red;
line-height: 200px;
text-align: center;
display: none;
}
.active{
display: block;
}
</style>
</head>
<body>
<div>
<ul class="clearfix">
<li>
<a href="#">首页</a>
</li>
<li>
<a href="#">新闻</a>
</li>
<li>
<a href="#">图片</a>
</li>
<p >首页内容</p>
<p>新闻内容</p>
<p>图片内容</p>
</ul>
<script>
oA=document.getElementsByTagName('a');
for(let i=0;i<oA.length;i++){
oA[i].onclick=function (){
for(let j=0;j<oA.length;j++){
oP=document.getElementsByTagName('p');
oP[j].className='';
oA[j].style.backgroundColor='#a5a6b0';
}
oA[i].style.backgroundColor='red';
oP[i].className='active';
}
}
</script>
</div>
</body>
二.定时器
(1)一次性定时器
可以做异步
(2)循环周期定时器
可以做动画
js的垃圾回收机制不回收定时器对象
1.开一次性定时器
var timer=setTimeout(fn,1000);
清一次性定时器
clearTimeout(timer)
实例:
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<button class="start">开启定时器</button>
<button class="end">关闭定时器</button>
<script>
var timer;
document.getElementsByClassName('start')[0].onclick=function(){
timer=setTimeout(function(){
alert('111')
},5000);
};
document.getElementsByClassName('end')[0].onclick=function(){
clearTimeout(timer);
};
</script>
</body>
2.开循环定时器
timer=setInterval(fn,1000);
清循环定时器
clearInterval(timer)
实例:
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
.box{
height: 100px;
width: 100px;
background-color: orangered;
}
</style>
</head>
<body>
<button class="start">开启定时器</button>
<button class="end">关闭定时器</button>
<div class="box"></div>
<script>
var timer;
var count=0;
document.getElementsByClassName('start')[0].onclick=function(){
clearInterval(timer);
timer=setInterval(function () {
count+=10;
oBox=document.getElementsByClassName('box')[0];
oBox.style.marginLeft=count+'px';
},500)
};
document.getElementsByClassName('end')[0].onclick=function(){
clearTimeout(timer);
};
</script>
</body>
三.JavaScript中的面向对象
1.使用Object或字面量方式创建对象
(1)使用Object内置的构造函数来创建对象
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
//创建student对象
var student=new Object();
//添加属性
student.name='沈珍珠';
student.age='18';
//添加方法
student.work=function(){
alert('战斗')
};
student.work();
</script>
</body>
(2)字面量方式创建
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
//创建一个student对象
var student={
//添加属性
name:'广平王',
//用逗号隔开
age:'19',
//添加方法
work:function(){
alert('皇位');
}
};
</script>
</body>
2.工厂模式创建对象
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<script>
function factory(){
var student=new Object();
student.name='魏璎珞';
student.work=function(){
alert('战斗');
};
return student;
}
var s1=factory();
s1.work();
var s2=factory();
</script>
</body>
3.自定义的构造函数模式创建对象
<body>
<script>
//为了与正常的函数区分,此处的函数名首字母要大写
function Person(name,age){
//此处的this相当于面向对象中的self
this.name=name;
this.age=age;
this.fav=function(){
alert(this.name);
}
}
function Fruit(name,age){
this.name=name;
this.age=age;
this.fav=function(){
alert(this.name);
}
}
//实例化时需要加一个new关键字
var f1=new Fruit('apple','18');
var p1=new Person('lili','18');
//instance用来检测前者是否是后者的实例,所有对象都是Object的实例
console.log(p1 instanceof Person);
console.log(f1 instanceof Fruit);
</script>
</body>
4.原型的模式创建对象
<body>
<script>
function Person(name,age){
this.name=name;
this.age=age;
}
//Person.prototype是Person的父类
//每一个实例化对象都继承prototype
Person.prototype.showName=function(){
//谁调用prototype,这里的this就是谁
console.log(this.name);
};
var p1=new Person('mimi',18);
p1.showName();
var p2=new Person('丽丽',19);
p2.showName()
</script>
</body>
改变世界,改变自己!
