I'm new with Angular promise and I would like to know how to improve my code.
I have a service which preload media or data by calling an API. The media API return an array of urls to preload.
'use strict';
angular.module('myApp').service('PreloaderService', ['$http', '$q', 'localStorageService', function PreloaderService($http, $q, localStorageService) {
this.preload = function(key){
var current = 0;
var deferred = $q.defer();
switch (key) {
case 'media':
// Simplified, in fact it call a config service to get baseUrl
var url = 'http://myapi/media';
$http.get(url, {cache: true}).then(function(data) {
var data = data.data;
preloadImage(data, localStorageService.get('cachetoken'));
}, function(data) {
deferred.reject(data);
});
break;
case 'data':
var url = 'http://myapi/data';
$http.get(url, {cache: true}).then(function(data) {
var data = data.data;
localStorageService.add('data', data);
deferred.resolve(data);
}, function(data) {
deferred.reject(data);
});
break;
}
function preloadImage(arrayOfImages, cachetoken) {
var promises = [];
var totalImg = arrayOfImages.length;
for (var i = 0; i < totalImg; i++) {
(function(url, promise) {
var img = new Image();
img.onload = function() {
var currentStatus = {
currentImg: ++current,
totalImg: totalImg
};
deferred.notify(currentStatus);
promise.resolve();
};
img.src = url + '&tok=' + cachetoken;
})(arrayOfImages[i], promises[i] = $.Deferred());
}
$.when.apply($, promises).done(function() {
deferred.resolve('RESOLVED');
}).fail(function(data) {
deferred.reject(data);
});
}
return deferred.promise;
};
}]);
And I call it with
var promise = Preloader.preload('media');
promise.then(
function(){
$rootScope.preload.imagesLoaded = true;
},
function(){},
function(currentStatus){
$rootScope.preload.currentImg = currentStatus.currentImg;
$rootScope.preload.totalImg = currentStatus.totalImg;
}
);