提示我TypeError: obj is undefined错误
今天按照老师讲的代码敲的时候遇到了一个问题，请大神们帮忙解答一下，谢谢各位
window.onload = function(){
var Li1 = document.getElementById('li1');
var Li2 = document.getElementById('li2');
Li1.onmouseover = function(){
startMove(this,'opacity',100);
}
Li1.onmouseout = function(){
startMove(this,'opacity',30);
}
}
function getStyle(obj,attr){
if(obj.currentStyle){
return obj.currentStyle[attr];
}
else{
return getComputedStyle(obj,false)[attr];
}
}
var alpha = 30;
function startMove(obj,attr,iTarget){
clearInterval(obj.timer);
obj.timer = setInterval(function(){
var icur = 0;
if(attr == 'opacity'){
icur = parseFloat(getStyle(obj.attr))*100;
}
else{
icur = parseInt(getStyle(obj,attr));
}
var speed = (iTarget - icur)/8;
speed = speed > 0?Math.ceil(speed):Math.floor(speed);
if(icur == iTarget){
clearInterval(obj.timer);
}
else{
if(attr == 'opacity'){
obj.style.filter = 'alpha(opacity:'+(icur + speed)+')';
obj.style.opacity = (icur + speed)/100;
}
else{
obj.style[attr] = icur + speed +'px';
}
}
},30);
}
