先说一下最土的一种方法：先说一下最土的一种方法：Html:





CSS:
h2 {

border-top: solid cornflowerblue 1px;

border-left: solid cornflowerblue 1px;

width: 50px;

height: 25px;

margin: 0;

float: left;

text-align: center;

}



.tab-content {

border: solid cornflowerblue 1px;

width: 152px;

height: 100px;

}



.tab-content div{

display: none;

}



.selected {

background-color: cornflowerblue;

}



.tab-content .show{

display: block;

}
h2 {

border-top: solid cornflowerblue 1px;

border-left: solid cornflowerblue 1px;

width: 50px;

height: 25px;

margin: 0;

float: left;

text-align: center;

}



.tab-content {

border: solid cornflowerblue 1px;

width: 152px;

height: 100px;

}



.tab-content div{

display: none;

}



.selected {

background-color: cornflowerblue;

}



.tab-content .show{

display: block;

}JS:
var tab1 = document.getElementById('tab1'),

tab2 = document.getElementById('tab2'),

tab3 = document.getElementById('tab3'),

c1 = document.getElementById('c1'),

c2 = document.getElementById('c2'),

c3 = document.getElementById('c3');


function changeTab1() {

tab1.className = 'selected';

tab2.className = '';

tab3.className = '';

c1.className = 'show'

c2.className = '';

c3.className = '';

}


function changeTab2() {

tab1.className = '';

tab2.className = 'selected';

tab3.className = '';

c1.className = '';

c2.className = 'show';

c3.className = '';

}


function changeTab3() {

tab1.className = '';

tab2.className = '';

tab3.className = 'selected';

c1.className = ''

c2.className = '';

c3.className = 'show';

}
var tab1 = document.getElementById('tab1'),

tab2 = document.getElementById('tab2'),

tab3 = document.getElementById('tab3'),

c1 = document.getElementById('c1'),

c2 = document.getElementById('c2'),

c3 = document.getElementById('c3');


function changeTab1() {

tab1.className = 'selected';

tab2.className = '';

tab3.className = '';

c1.className = 'show'

c2.className = '';

c3.className = '';

}


function changeTab2() {

tab1.className = '';

tab2.className = 'selected';

tab3.className = '';

c1.className = '';

c2.className = 'show';

c3.className = '';

}


function changeTab3() {

tab1.className = '';

tab2.className = '';

tab3.className = 'selected';

c1.className = ''

c2.className = '';

c3.className = 'show';

}效果：实现Tab的切换，我们很容易想到的一种方式就是给每一个要控制的标签添加id，然后分别编写鼠标事件，使用id获取每个元素，精确地控制每个元素的样式。这种方式的缺点显而易见，有几个元素就有几个id，每个tab都要编写function，里面的方法大同小异。要增加tab的话，还要增加id和function，代码冗余，不易扩展。第二种较为高明些的方法是编写一个function，将每个元素的序号传进去。第二种第二种Html：





JS：
var tabs = document.getElementsByClassName('tab-head')[0].getElementsByTagName('h2'),

contents = document.getElementsByClassName('tab-content')[0].getElementsByTagName('div');


function changeTab(index) {

for(var i = 0, len = tabs.length; i < len; i++) {

if(i === index) {

tabs[i].className = 'selected';

contents[i].className = 'show';

}else{
tabs[i].className = '';

contents[i].className = '';
}

}

}
var tabs = document.getElementsByClassName('tab-head')[0].getElementsByTagName('h2'),

contents = document.getElementsByClassName('tab-content')[0].getElementsByTagName('div');


function changeTab(index) {

for(var i = 0, len = tabs.length; i < len; i++) {

if(i === index) {

tabs[i].className = 'selected';

contents[i].className = 'show';

}else{
tabs[i].className = '';

contents[i].className = '';
}

}

}这样就只要写一个function了，而且不需要id，但是还是要按照顺序传递参数。第三种方式和第二种基本一样，只是参数传递的是this指针。第三种Html：





JS：
var tabs = document.getElementsByClassName('tab-head')[0].getElementsByTagName('h2'),

contents = document.getElementsByClassName('tab-content')[0].getElementsByTagName('div');


function changeTab(tab) {

for(var i = 0, len = tabs.length; i < len; i++) {

if(tabs[i] === tab) {

tabs[i].className = 'selected';

contents[i].className = 'show';

} else {

tabs[i].className = '';

contents[i].className = '';

}

}

}
var tabs = document.getElementsByClassName('tab-head')[0].getElementsByTagName('h2'),

contents = document.getElementsByClassName('tab-content')[0].getElementsByTagName('div');


function changeTab(tab) {

for(var i = 0, len = tabs.length; i < len; i++) {

if(tabs[i] === tab) {

tabs[i].className = 'selected';

contents[i].className = 'show';

} else {

tabs[i].className = '';

contents[i].className = '';

}

}

}这种方式稍微方便一些，只要传递this指针，不用按照顺序传递序号，但这也不是最简便的方式。最简便的一种：第四种方式：第四种Html：





JS：
var tabs = document.getElementsByClassName('tab-head')[0].getElementsByTagName('h2'),

contents = document.getElementsByClassName('tab-content')[0].getElementsByTagName('div');


(function changeTab(tab) {

for(var i = 0, len = tabs.length; i < len; i++) {

tabs[i].onmouseover = showTab;

}

})();


function showTab() {

for(var i = 0, len = tabs.length; i < len; i++) {

if(tabs[i] === this) {

tabs[i].className = 'selected';

contents[i].className = 'show';

} else {

tabs[i].className = '';

contents[i].className = '';

}

}

}
var tabs = document.getElementsByClassName('tab-head')[0].getElementsByTagName('h2'),

contents = document.getElementsByClassName('tab-content')[0].getElementsByTagName('div');


(function changeTab(tab) {

for(var i = 0, len = tabs.length; i < len; i++) {

tabs[i].onmouseover = showTab;

}

})();


function showTab() {

for(var i = 0, len = tabs.length; i < len; i++) {

if(tabs[i] === this) {

tabs[i].className = 'selected';

contents[i].className = 'show';

} else {

tabs[i].className = '';

contents[i].className = '';

}

}

}这样JS、Html、CSS就完全分离了，通过this指针就可以判断当前鼠标滑过的是哪一个tab了。