angular file upload preview module

upload_preview.js

(function (module) {
  "use strict";

  var fileReader = function ($q) {

    var onLoad
      , onError
      , onProgress
      , getReader
      , readAsDataURL
      ;

    onLoad = function (reader, deferred, scope) {
      return function () {
        scope.$apply(function () {
          deferred.resolve(reader.result);
        });
      };
    };

    onError = function (reader, deferred, scope) {
      return function () {
        scope.$apply(function () {
          deferred.reject(reader.result);
        });
      };
    };

    onProgress = function (reader, scope) {
      return function (event) {
        scope.$broadcast("fileProgress",
          {
            total: event.total,
            loaded: event.loaded
          });
      };
    };

    getReader = function (deferred, scope) {
      var reader = new FileReader();
      reader.onload = onLoad(reader, deferred, scope);
      reader.onerror = onError(reader, deferred, scope);
      reader.onprogress = onProgress(reader, scope);
      return reader;
    };

    readAsDataURL = function (file, scope) {
      var deferred = $q.defer()
        , reader = getReader(deferred, scope)
        ;

      reader.readAsDataURL(file);

      return deferred.promise;
    };

    return {
      readAsDataUrl: readAsDataURL
    };
  };

  module.factory("fileReader", ["$q", fileReader]);

}(window.angular.module("app")));