style.top style.left 在IE和FireFox的区别

在IE中可以直接用obj.style.top=100;但在FireFox中必须加上单位，变成obj.style.top=100+'px';
style.left同理。

浏览器的判断：window.navigator.userAgent.indexOf("IE") == -1 //非IE浏览器  FireFox,Chrome

FireFox没有onmouseover和onmouseout,onclick事件,他们的写法为：

if (window.navigator.userAgent.indexOf( " IE " )  ==   - 1 )  // FireFox
{
     link.addEventListener( ' mouseover ' ,  function (){a  =   false },  true );
     link.addEventListener( " mouseout " , function (){a  =   true }, true )
}
else   // IE
{
     link.attachEvent( " onmouseover " , function (){a  =   false });
     link.attachEvent( " onmouseout " , function (){a  =   true });
}