Fiddle Links: Source code – Preview – Small version
Update: This small function will only execute code in a single direction. If you want full support (eg event listeners / getters), have a look at Listening for Youtube Event in jQuery
As a result of a deep code analysis, I’ve created a function: function callPlayer requests a function call on any framed YouTube video. See the YouTube Api reference to get a full list of possible function calls. Read the comments at the source code for an explanation.
On 17 may 2012, the code size was doubled in order to take care of the player’s ready state. If you need a compact function which does not deal with the player’s ready state, see http://jsfiddle.net/8R5y6/.
/**
* @author Rob W <gwnRob@gmail.com>
* @website http://stackoverflow.com/a/7513356/938089
* @version 20120724
* @description Executes function on a framed YouTube video (see website link)
* For a full list of possible functions, see:
* https://developers.google.com/youtube/js_api_reference
* @param String frame_id The id of (the div containing) the frame
* @param String func Desired function to call, eg. "playVideo"
* (Function) Function to call when the player is ready.
* @param Array args (optional) List of arguments to pass to function func*/
function callPlayer(frame_id, func, args) {
if (window.jQuery && frame_id instanceof jQuery) frame_id = frame_id.get(0).id;
var iframe = document.getElementById(frame_id);
if (iframe && iframe.tagName.toUpperCase() != 'IFRAME') {
iframe = iframe.getElementsByTagName('iframe')[0];
}
// When the player is not ready yet, add the event to a queue
// Each frame_id is associated with an own queue.
// Each queue has three possible states:
// undefined = uninitialised / array = queue / 0 = ready
if (!callPlayer.queue) callPlayer.queue = {};
var queue = callPlayer.queue[frame_id],
domReady = document.readyState == 'complete';
if (domReady && !iframe) {
// DOM is ready and iframe does not exist. Log a message
window.console && console.log('callPlayer: Frame not found; id=' + frame_id);
if (queue) clearInterval(queue.poller);
} else if (func === 'listening') {
// Sending the "listener" message to the frame, to request status updates
if (iframe && iframe.contentWindow) {
func = '{"event":"listening","id":' + JSON.stringify(''+frame_id) + '}';
iframe.contentWindow.postMessage(func, '*');
}
} else if (!domReady || iframe && (!iframe.contentWindow || queue && !queue.ready)) {
if (!queue) queue = callPlayer.queue[frame_id] = [];
queue.push([func, args]);
if (!('poller' in queue)) {
// keep polling until the document and frame is ready
queue.poller = setInterval(function() {
callPlayer(frame_id, 'listening');
}, 250);
// Add a global "message" event listener, to catch status updates:
messageEvent(1, function runOnceReady(e) {
var tmp = JSON.parse(e.data);
if (tmp && tmp.id == frame_id && tmp.event == 'onReady') {
// YT Player says that they're ready, so mark the player as ready
clearInterval(queue.poller);
queue.ready = true;
messageEvent(0, runOnceReady);
// .. and release the queue:
while (tmp = queue.shift()) {
callPlayer(frame_id, tmp[0], tmp[1]);
}
}
}, false);
}
} else if (iframe && iframe.contentWindow) {
// When a function is supplied, just call it (like "onYouTubePlayerReady")
if (func.call) return func();
// Frame exists, send message
iframe.contentWindow.postMessage(JSON.stringify({
"event": "command",
"func": func,
"args": args || [],
"id": frame_id
}), "*");
}
/* IE8 does not support addEventListener... */
function messageEvent(add, listener) {
var w3 = add ? window.addEventListener : window.removeEventListener;
w3 ?
w3('message', listener, !1)
:
(add ? window.attachEvent : window.detachEvent)('onmessage', listener);
}
}Usage:
callPlayer("whateverID", function() {
// This function runs once the player is ready ("onYouTubePlayerReady")
callPlayer("whateverID", "playVideo");
});
// When the player is not ready yet, the function will be queued.
// When the iframe cannot be found, a message is logged in the console.
callPlayer("whateverID", "playVideo");Possible questions (& answers):
Q: It doesn’t work!
A: "Doesn’t work" is not a clear description. Do you get any error messages? Please show the relevant code.
Q: I have embedded a YouTube video using <iframe src="http://www.youtube.com/embed/As2rZGPGKDY" />but the function doesn’t execute any function!
A: You have to add ?enablejsapi=1 at the end of your URL: /embed/vid_id?enablejsapi=1.
Q: I get error message "An invalid or illegal string was specified". Why?
A: The API doesn’t function properly at a local host (file://). Host your (test) page online, or useJSFiddle. Examples: See the links at the top of this answer.
Q: How did you know this?
A: I have spent some time to manually interpret the API’s source. I concluded that I had to use thepostMessage method. To know which arguments to pass, I created a Chrome extension which intercepts messages. The source code for the extension can be downloaded here.
Q: What browsers are supported?
A: Every browser which supports JSON and postMessage.
- IE 8+
- Firefox 3.6+ (actually 3.5, but
document.readyStatewas implemented in 3.6) - Opera 10.50+
- Safari 4+
- Chrome 3+
Related answer / implementation: Fade-in a framed video using jQuery
Full API support: Listening for Youtube Event in jQuery
Revision history
- 17 may 2012
ImplementedonYouTubePlayerReady:callPlayer('frame_id', function() { ... }).Functions are automatically queued when the player is not ready yet.
- 24 july 2012
Updated and successully tested in the supported browsers (look ahead).