this的指向:
1 //this 指的是调用 当前方法 （函数） 的那个对象 2 3 function fn1(){ 4 this; 5 } 6 7 //fn1(); this => window 8 //obj.onclick=fn1; this=>obj 9 //obj.onclick=function(){ this; } this=>window;
this的应用:
1 <!DOCTYPE html> 2 <html> 3 <head> 4 <meta charset="utf-8" /> 5 <title></title> 6 <style type="text/css"> 7 *{margin: 0;padding: 0;} 8 ul,li{list-style: none;} 9 li { width:100px; height:150px; float:left; margin-right:30px; background:#f1f1f1; position:relative; z-index:1; } 10 div { width:80px; height:200px; background:red; position:absolute; top:75px; left:10px; display:none; } 11 </style> 12 <script type="text/javascript"> 13 window.onload=function(){ 14 var oUl=document.getElementById("ul1"); 15 var aLi=oUl.getElementsByTagName("li"); 16 17 for(var i=0;i<aLi.length;i++){ 18 aLi[i].onmouseover=function(){ 19 this.getElementsByTagName("div")[0].style.display="block"; 20 }; 21 aLi[i].onmouseout=function(){ 22 this.getElementsByTagName("div")[0].style.display="none"; 23 }; 24 }; 25 }; 26 </script> 27 </head> 28 <body> 29 <ul id="ul1"> 30 <li><div></div></li> 31 <li><div></div></li> 32 <li><div></div></li> 33 <li><div></div></li> 34 </ul> 35 </body> 36 </html>
原文：http://www.cnblogs.com/trtst/p/3751764.html