ES6 Async constructors

example.js

/*
 * Ecmascript supports the `async` keyword to make functions async.
 * Unfortunately it doesn't work on construcors.
 * 
 * However: you can return in a constructor!
 */

(async() => { // for top level await
	class Example {
		// ES6 constructor
		constructor() {
			// Return a promise
			return this.construct() // our async function
				.then(self => self || this); // make sure we return something, if our `construct()` implementation returns nothing (undefined) use `this`
		}
    
		// our "actual" constructor
		async construct() {
			// return a promise that resolved after 1 second
			// this could for example retrieve information from an http api instead
			await new Promise(resolve => setTimeout(resolve, 1000));
		}
	}

	console.time('construct');
	await new Example();
	console.timeEnd('construct'); // Will print about 1 second (1000ms)
})(); // for top level await