Created: 2014-05-18 14:41
Updated: 2018-04-30 21:48
License: mit

Friendly Cast

If you've ever tried using the official Google Cast API (Chromecast API), you know my frustration. It's very verbose and unintuitive, and there is no good reason for it. After about a day of working with this API, I had enough and decided to make my life a bit easier. There is no reason such a simple platform should have such a high barrier to entry. Now, we can all have a modern JavaScript API for the Chromecast.


In similarity with Google, this API wrapper is a developer preview. It was made in only a few hours, after spending an entire frustrating day trying to work with the official API. I am currently only focusing on video content, but support will expand eventually. I am actively breaking this right now, as you read this. Don't worry, it will be stable soon.

The events and errors need more work, as I am not certain what they all mean at the moment. Further, I will need to do a bit more work to fully support custom receivers.

If you are a Chromecast veteran, or have any ideas or request, feel free to submit a issue or pull request, or contact me on Google+.

How to use it

Load both this library and the official Google Cast API, as such

<script src="chromecast.js"></script>
<script type="text/javascript" src=""></script>

No more waiting for the Cast API to be ready/initialize/etc. After the scripts are loaded, you are ready to go. The Friendly Cast wrapper will handle the hard work of initializing everything. To start, provide your applicationID if you have a registered receiver, or leave it blank to use the default media player:


// OR

var applicationID = 'xxxxxxxxxxxxxxxxxxxxxxx';

Yes, folks, it's that easy. When the user tells you which video to play, just provide the URL to the Friendly Cast wrapper, and you are done:

var urlString = 'http://server/path/to/video.mp4';

Some advanced uptions:

var urlString = 'http://server/path/to/video.mp4';
chromecast.startCast(urlString, {
    title: 'Pretty Video Name',

Media controls

Controlling the playing media is pretty simple as well:


Seeking is done in seconds, relative to the beginning of the video. To seek to 5 minutes into the video:

var time = 5 * 60;;

Volume settings:

//sets the Chromecast to 50% volume
//this value is any number between 0 and 1

//mutes the Chromecast

//returns the Chromecast to the volume level before `mute`

Stopping the video is also simple. However, note that stopping the video causes you to lose the media object, and you will need to play a new video to continue:


//this will do nothing;

//play a new video (or the same one again)

There are some auxiliary methods in the media control object as well:

//returns the total time in seconds

//return the current time in seconds

//return the current status of the player
//this will be the same status as the default Google Cast API


Rather than providing a million callback functions every step of the way, Friendly Cast emits events using a familiar on/off system.

chromecast.on('available', function(ev){
    var urlString = 'http://server/path/to/video.mp4';

To remove and event, pass in the name and original function:

var doSomething = function(){ ... };

//subscribe to an event
chromecast.on('available', doSomething);

//unsubscribe to the event'available', doSomething);

//subscribe and fire only once
chromecast.once('available', doSomething);

To find out all of the available events, you can check out the chromecast.Events enumerable in the Chrome console. I also suggest you use this enumerable to subscribe to events:

chromecast.on(chromecast.Events.ready, function(){
    //the Google Cast API is available

Some events you might care about:

  • mediaDiscovered: Event is fired when the media starts. This is the name Chromecast uses, so I use it too. Sorry that it's confusing.

  • mediaControl: Event is issued any time you request to change something about the media. This event will tell you what command triggered it.

    chromecast.on(chromecast.Events.mediaEnd, function(ev){ ev.command; // {string} the command that triggered it ev.success; // {bool} whether the command was successful

      // if there is an error, `ev` might have extra stuff in it
      // that was provided by Chrome


  • mediaEnd: Event is triggered when the media playing has ended. Doesn't provide any special information.

More documentation will come on events as I have it. In the meantime, you can see all of the events if you observe the chromecast.Events object. Subscribe to the ones you think you might need and console.log the event to see what it provides.


The Google Cast API has quite a few errors it provides. I have standardized them all under teh error event:

chromecast.on(chromecast.Events.error, function(err){
    err.message; // corresponds to the closest equivalent name of the Google Cast API
    err.permanent; //if this is true, Google Cast has had a permanent error, requiring a page refresh
    err.args; //this is the original error arguments as provided by the Google Cast API

More documentation will come on errors as I have it.

What next?

Sit tight for more coverage of the API, including more media types. In the meantime, you can still use the regular Google Cast API to continue, or use the chromecast.session and objects to access the current session.


All code here is licensed under the MIT X11 License.


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