function loadImage(imgList,callback){
if(!Array.isArray(imgList) || callback.constructor !== Function) {console.log('lost');return ;}
var imageData = [] ;
imgList.forEach(function(src,i){
var img = new Image() ;
img.onload = function(){
body.appendChild(imageData.shift());
if(!imageData.length){
callback() ;
return ;
}
this.onload = null ;
} ;
img.src= src ;
imageData.push(img) ;
}) ;
} ;