Javascript Callback function scope issue -

i having trouble in

how assign value in callback function?

thanks rodik have general idea of how it. however, still not sure how pass img value getimage function...

project.prototype.getimagepath = function(){     codes...     this.getfolder(path);     //how img value inside getimage function? }   project.prototype.getfolder = function(path){  this.imagepath; var instance = this; var images = ['http://project/path.png', 'http://project2/path.png'];     function getimage(images, callback) {         var iterator = function (i) {            if (i < images.length) {                      var image = newimage();                      //..codes check if image path valid                      //if valid, pass image                         callback(image);                      }                      iterator(++i);           }         }         iterator(0);     }      getimage(images, function (img) {        console.log(img)  //output img         instance.imagepath = img    });  } 

thanks guys~~