By using Promises you can delay the rendering of the list until you have successfully composed the temporary list with your tracks. Also, in order to prevent the addition of repeated tracks on reload, assign a unique name to your temporary playlist.
require([
'$api/models',
'$views/list#List',
'$api/toplists#Toplist'
], function (models, List, Toplist) {
'use strict';
// Build playlist
function buildList(trackURIArray) {
var arr = trackURIArray;
models.Playlist
.createTemporary("myTempList_" + new Date().getTime())
.done(function (playlist) {
playlist.load("tracks").done(function () {
playlist.tracks.add.apply(playlist.tracks, arr).done(function () {
// Create list
var list = List.forCollection(playlist, {
style: 'rounded'
});
$('#playlistContainer').appendChild(list.node);
list.init();
});
});
});
}
// Get top track
function getTopTrack(artist, num) {
var promise = new models.Promise();
var artistTopList = Toplist.forArtist(artist);
artistTopList.tracks.snapshot(0, num).done(function (snapshot) {
snapshot.loadAll().done(function (tracks) {
promise.setDone(tracks[0]);
}).fail(function (f) {
promise.setFail(f);
});
});
return promise;
}
// Get Related
function getRelated(artist_uri) {
models.Artist
.fromURI(artist_uri)
.load('related')
.done(function (artist) {
artist.related.snapshot().done(function (snapshot) {
snapshot.loadAll().done(function (artists) {
var promises = [];
for (var i = 0; i < artists.length; i++) {
var promise = getTopTrack(artists[i], 1);
promises.push(promise);
}
models.Promise.join(promises)
.done(function (tracks) {
console.log('Loaded all tracks', tracks);
})
.fail(function (tracks) {
console.error('Failed to load at least one track.', tracks);
})
.always(function (tracks) {
// filter out results from failed promises
buildList(tracks.filter(function(t) {
return t !== undefined;
}));
});
});
});
});
}
getRelated('spotify:artist:2VAvhf61GgLYmC6C8anyX1');
});