top-level await vs. async IIFE

top-level-await-vs-async-iife.js

// 17 May 2020
// top-level await vs. async IIFE

// Works in Chrome & Firefox
// Does not work in Edge (throws 'await' is not defined)
await (function() { return Promise.resolve('top-level await') })().then(console.warn);

// > "top-level await"

// async IIFE works across all 3 browsers here
// async goes inside the parentheses, else it's parsed as `async(fn)` 
// which throws "ReferenceError: async is not defined"
(async function() {
	return await (function() { return Promise.resolve('async IIFE') })();
})().then(console.warn);

// > "async IIFE"