使用setInterval实现渐隐藏

//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);

}