//使用setInterval实现渐隐藏
function myFadeout(ele){
var target = 1,
speed = 1/50;
var timer = setInterval(function(){
if(!parseFloat(ele.style.opacity) > 0){
ele.style.opacity = 1;
}
if(target>0){
target -= speed;
ele.style.opacity = target;
}else{
ele.style.opacity = 0;
clearInterval(timer);
}
}, 20);
}
调用：ele为已经获取到的HTML元素，
ele=document.getElementById('x');
