js实现遮罩层划出效果是生成div而不是显示

var getOneDiv=function(){ 

var div=document.createElement("div"); 
div.style.position="absolute"; 
div.style.display="block"; 
div.style.zIndex="10"; 
div.style.background="yellow"; 
div.addEventListener("mouseout",function(event){//我把它加在了这里，而这里监听的判断与之前的划入几乎如出一辙 
var x=event.clientX; 
var y=event.clientY; 
left=x-test.offsetLeft; 
top=y-test.offsetTop; 
right=test.offsetLeft+test.offsetWidth-x; 
bottom=test.offsetTop+test.offsetHeight-y; 
arr=[]; 
arr.push(top); 
arr.push(right); 
arr.push(bottom); 
arr.push(left); 
var least=findLeast(arr); 


if(least==1){ 
} 
if(least==2){//还是距离和宽度的同时改变啊 
div.style.left=test.offsetLeft+"px"; 
div.style.top=test.offsetTop+"px"; 
div.style.height=test.offsetHeight+"px"; 
div.style.width=width+"px"; 
var changeWidth2=setInterval(function(){ 
if(div.offsetLeft>=test.offsetLeft+test.offsetWidth){ 
clearInterval(changeWidth2); 
check=true;//关键点 
}else{ 
marginLeft=marginLeft+10; 
width=width-10; 
div.style.width=width+"px"; 
div.style.left=marginLeft+"px"; 
} 
},30); 
} 
if(least==3){ 

} 
if(least==4){//向左划出，width作为全局变量，这次就是不断减小了 
div.style.left=test.offsetLeft+"px"; 
div.style.top=test.offsetTop+"px"; 
div.style.height=test.offsetHeight+"px"; 
div.style.width=width+"px"; 
var changeWidth1=setInterval(function(){ 
if(div.offsetWidth<=0){ 
clearInterval(changeWidth1); 
check=true;//这里也比较关键哦 
}else{ 
width=width-10; 
div.style.width=width+"px"; 
} 
},30); 
} 
}) 
return div; 
}