主干采集长度为0

应用程序代码段:

handleFileSelect: function(evt) {

var files = evt.target.files; // FileList object
        var collection = new Backbone.Collection();
        collection.on('complete',this.renderImg);
        var x = 5;
for (var i = 0;i<files.length;i++) {
            var f = files[i];
            var reader = new FileReader();

闭包捕获文件信息。

reader.onload = (function (theFile,collection) {
                return function (e) { 

add models in collection

collection.add(new Backbone.Model({title:theFile.name,src:e.target.result}));       
    };

     })(f,collection);
                // Read in the image file as a data URL.
                reader.readAsDataURL(f);
            }
            return collection;
        }

集合返回，长度为0，即集合中没有模型，请?