2019js13k/js/autoload.js

var pendingClasses = [];
var loadedClasses = [];
var autoloader = (classname) => {
	if (pendingClasses.indexOf(classname) != -1) {
		return Promise.resolve();
	}
	pendingClasses.push(classname);
	return new Promise((resolve, reject) => {
		if (loadedClasses.indexOf(classname) != -1) {
			pendingClasses.splice(pendingClasses.indexOf(classname), 1);
			resolve();
		}

		let url = `./js/${classname}.js`;
		if (window.cacheBust) {
			url += "?v=" + new Date().getTime();
		}
		let script = document.createElement("script");
		script.src = url;
		script.type = "text/javascript";
		script.async = true;
		script.addEventListener('load', (event) => {
			pendingClasses.splice(pendingClasses.indexOf(classname), 1);
			loadedClasses.push(classname);
			resolve();
		});
		script.addEventListener('error', () => {
			reject(new Error(`Unable to load ${classname}: attempted location ${url}`));
		});
		document.getElementsByTagName("body")[0].appendChild(script);
	});
};

var require = (classname) => {
	autoloader(classname).then(() => {
		let event = new CustomEvent("JSScriptLoaded", { detail: { classname: classname } });
		document.dispatchEvent(event);
	}).catch((e) => {
		console.error(e);
	});
};

document.addEventListener("JSScriptLoaded", (event) => {
	if (pendingClasses.length <= 0) {
		let event = new CustomEvent("JSContentLoaded", { detail: { classes: loadedClasses } });
		document.dispatchEvent(event);
	}
});