Async Load JavaScript Files with Callback
- by Gcoop
Hi All,
I am trying to write an ultra simple solution to load a bunch of JS files asynchronously. I have the following script below so far. However the callback is sometimes called when the scripts aren't actually loaded which causes a variable not found error. If I refresh the page sometimes it just works because I guess the files are coming straight from the cache and thus are there quicker than the callback is called, it's very strange?
var Loader = function () {
}
Loader.prototype = {
require: function (scripts, callback) {
this.loadCount = 0;
this.totalRequired = scripts.length;
this.callback = callback;
for (var i = 0; i < scripts.length; i++) {
this.writeScript(scripts[i]);
}
},
loaded: function (evt) {
this.loadCount++;
if (this.loadCount == this.totalRequired && typeof this.callback == 'function') this.callback.call();
},
writeScript: function (src) {
var self = this;
var s = document.createElement('script');
s.type = "text/javascript";
s.async = true;
s.src = src;
s.addEventListener('load', function (e) { self.loaded(e); }, false);
var head = document.getElementsByTagName('head')[0];
head.appendChild(s);
}
}
Is there anyway to test that a JS file is completely loaded, without putting something in the actual JS file it's self, because I would like to use the same pattern to load libraries out of my control (GMaps etc).
Invoking code, just before the tag.
var l = new Loader();
l.require([
"ext2.js",
"ext1.js"],
function() {
var config = new MSW.Config();
Refraction.Application().run(MSW.ViewMapper, config);
console.log('All Scripts Loaded');
});
Thanks for any help.
