function $(id) {

?return typeof id==='string'?document.getElementById('id'):id;

}

window.onload = function() {

? //獲取鼠標(biāo)劃過(guò)或點(diǎn)擊的標(biāo)簽和要切換內(nèi)容的元素

var titles = $('tit').getElementsByTagName('li');

var divs = $('con').getElementsByTagName('div');

if(titles.length != divs.length);

return;

//遍歷titles下所有的li

for( var i = 0; i < titles.length; i++) {

titles[i].id = i;

titles[i].onmouseover = function(){

for( var j = 0; j < titles.length; j++) {

?titles[i].className = "";

?divs[i].style.display = "none";

}

this.className = "select";

divs[this.id].style.display = "block";

} ?

}

??

}