I had a more expansive issue that boiled down to this same problem. The requirements I had were to write a JS class to manage one or more (the number can vary from 1 to infinity) video embeds. The backend system is ExpressionEngine (but that's irrelevant here). The primary goal was to set up a framework for analytics that pushes individual data to our Adobe Analytics platform. Shown here is merely the part that gives play count, it can be expanded a lot from here.
The CMS allows editors to create modules on the page that present a video. One video per module. Each module is basically a section of HTML arranged via Bootstrap 3 (irrelevant for this answer).
The relevant HTML looks like this:
<div id="js_youTubeContainer_{innov_mod_ytplayer:id}" class="embed-responsive embed-responsive-16by9">
<div id="js_youTubeFrame_{innov_mod_ytplayer:id}" class="embed-responsive-item"></div>
</div>
The part that says "{innov_mod_ytplayer:id}" is the YouTube Video ID from our CMS. This allows for a unique ID for each embeded item. This is important later.
Below this, I then render out:
var innovYouTube_{innov_mod_ytplayer:id} = new Ariba.Innovations.YouTube.Class({
'innovYouTubeVideoId': '{innov_mod_ytplayer:id}',
'innovYouTubeVideoTitle': '{innov_mod_ytplayer:title}',
'innovYouTubeDivId' : 'js_youTubeFrame_{innov_mod_ytplayer:id}'
});
innovYouTube_{innov_mod_ytplayer:id}.Init(); // And... Go!
var onYouTubeIframeAPIReady = (function() {
try{ //wrap this in try/catch because it actually throws errors when it runs subsequent times - this is expected as it's related to YouTube "rerunning" the function on other videos.
innovYouTube_{innov_mod_ytplayer:id}.config.functionCache = onYouTubeIframeAPIReady; //cache the existing global function
return function() {
try{
innovYouTube_{innov_mod_ytplayer:id}.onYouTubeIframeAPIReady(); //execute this instance's function
var newOnYouTubeIframeAPIReady = innovYouTube_{innov_mod_ytplayer:id}.config.functionCache.apply(this, arguments); //add instances to global function
return newOnYouTubeIframeAPIReady; //update global function
}catch(err){}
};
}catch(err){}
})();
You'll see some ExpressionEngine template tags here too - those are just the Video ID and the Video Title from YouTube. To replicate this, you'll need to change those of course.
What this does is allow me to dynamically update the single global callback with new code for each newly embedded video. In the end, this callback will contain calls to their own instances of my class. You need those try/catch blocks because it throws a false-positive error for all the "other" embeds except the one it's actually executing "right now" - remember this script runs once for every embed on the page. The errors are expected and actually cause no problem, so the try/catch suppresses them.
Using the CMS template tag, I create each instance based on the YouTube video ID. I would run into a problem if someone added the same video module more than once, but that's a business problem easily handled since that's not supposed to happen. This allows me to instantiate unique instances of my class over and over for each video.
The critical part of that script is based on this extremely helpful SO answer: Adding code to a javascript function programmatically
Here's the actual class. It's commented mostly... We use jQuery, so you'll see one important use of it here in the $.extend() method. I use that as a convenience in the class constructor method, but you could do that with vanilla JS too (JavaScript equivalent of jQuery's extend method) I just find the jQuery easier to read, and since it's available to me, I use it.
if (typeof Ariba === "undefined") { var Ariba = {}; }
if (typeof Ariba.Innovations === "undefined") { Ariba.Innovations = {}; }
if (typeof Ariba.Innovations.YouTube === "undefined") { Ariba.Innovations.YouTube = {}; }
if (typeof Ariba.Innovations.YouTube.Class === "undefined") {//this script may be embedded more than once - do this to avoid re-processing it on subsequent loads
Ariba.Innovations.YouTube.Class = function (config) {
this.static = {
'ytScriptId': 'js_youtubeFrameAPI',
'ytScriptUrl': 'https://www.youtube.com/iframe_api'
};//static configuration. Will overwrite any other settings with the same name
this.config = {//optional configuration variables. Will be overridden by instance or static settings with the same name.
'adobeAnalyticsFired': false
};
this.config = $.extend(true, this.config, config);//inserts (destructively!) the instance settings.
this.config = $.extend(true, this.config, this.static);//inserts (destructively!) the static settings.
this.config.this = this;
};
Ariba.Innovations.YouTube.Class.prototype.Init = function () {
//Note: have to allow it to write it over an over because calling the API script is what makes YouTube call onYouTubeIframeAPIReady.
//if (document.getElementById('js_youtubeFrameAPI') === null) { // don't add the script again if it already exists!
this.config.apiScript = document.createElement('script');
this.config.apiScript.src = 'https://www.youtube.com/iframe_api';
this.config.apiScript.id = 'js_youtubeFrameAPI' + this.config.innovYouTubeVideoId;
this.config.firstScriptTag = document.getElementsByTagName('script')[0];
this.config.firstScriptTag.parentNode.insertBefore(this.config.apiScript, this.config.firstScriptTag);
//}
//else { console.log("iframe script already embedded", this.config.innovYouTubeVideoId); }
}
Ariba.Innovations.YouTube.Class.prototype.onYouTubeIframeAPIReady = function (event) {
//console.log("onYouTubeIframeAPIReady", this.config.innovYouTubeVideoId, arguments);
var _this = this;
//console.log(this);
this.config.ytPlayer = new YT.Player(this.config.innovYouTubeDivId, {
videoId: this.config.innovYouTubeVideoId,
events: {
'onReady': _this.onPlayerReady.bind(_this),
'onStateChange': _this.onPlayerStateChange.bind(_this)
}
});
}
Ariba.Innovations.YouTube.Class.prototype.onPlayerReady = function (event) {
//console.log("onPlayerReady", this.config.innovYouTubeVideoId, event);
}
Ariba.Innovations.YouTube.Class.prototype.onPlayerStateChange = function (event) {
//console.log("onPlayerStateChange", this.config.innovYouTubeVideoId, event, this);
if (event.data === YT.PlayerState.PLAYING && !this.config.adobeAnalyticsFired) {
//console.log("YouTube Video is PLAYING!!", this.config.innovYouTubeVideoId);
this.config.adobeAnalyticsFired = true;
if (typeof _satellite !== "undefined") {
window._satellite.data.customVars.adhoc_tracker_val = "Innovations Video: " + this.config.innovYouTubeVideoTitle + " (" + this.config.innovYouTubeVideoId + ")";
_satellite.track('adhoctrack');
}
}
}
}
A few other notes:
Keeping scope in the class instance is easy once you get the main global callback problem solved. You just have to add .bind(). For example:
'onReady': _this.onPlayerReady.bind(_this)
You might also see:
var _this = this;
This is so the "this" scope for the instance isn't lost accidentally. Maybe not necessary, but it's a convention I've adopted over the years.
Anyway, I've been working on this for a week now, and figured I'd share it with the SO community since it's clear from my looking for answers a lot of others have been searching for solutions to this too.
function createPlayer(playerInfo) { return new YT.Player(playerInfo.id, { videoId: playerInfo.videoId, events: { 'onReady': onPlayerReady, 'onStateChange': onPlayerStateChange } }); } function onPlayerReady(event) { console.log('ready'); }
– Chanty