JavaScript Async/Await and the Event Loop Explained
Run this in Node or a browser console: 1 2 3 4 console.log("1"); setTimeout(() => console.log("2"), 0); Promise.resolve().then(() => console.log("3")); console.log("4"); The output is 1 4 3 2. A setTimeout with a 0ms delay still runs after the promise callback, and both wait for every line of synchronous code below them. async/await is built on this ordering, not on something new. Most of the surprising behavior in async JavaScript comes from writing await as if it paused the whole program, when it only pauses the function it’s in. ...