Preloading of images

//Picture preload 
function YReload(result,imgName,callBack){ 
   var imgArr = []; 
   for(var i in result){ 
        (function(item,src){ 
            if(IsPicture(src)){//Get the picture path 
                imgArr[i] = new Image(); 
                imgArr[i].src = src; 
                imgArr[i].onload = function(){ 
                    callBack(item); 
                }; 
            } 
        })(result[i],result[i ][imgName]); 
   } 

} 

//Determine whether it is a picture 
function IsPicture(str) 
{ 
     //Determine whether it is a picture - strFilter must be a lowercase list 
     var strFilter=".jpeg|.gif|.jpg|.png|.bmp |.pic|" 
     if(str.indexOf(".")>-1) 
     {
         return true;
         var p = str.lastIndexOf(".");
         var strPostfix=str.substring(p,this.length) + '|';
         strPostfix = strPostfix.toLowerCase();
         if(strFilter.indexOf(strPostfix)>-1)
         {
             return true;
         }
     }
     return false;
 }

//调用

var result = success.data.data.list
          YReload(result,'videoAudioLogo',function(item){
                 that.learningContent.push(item)
});