The Event Loop, Visualized

async/await, unmasked — interactive event loop example

1async function order() {
2  console.log('ordering');
3  await Promise.resolve();
4  console.log('order arrived');
5}
6 
7order();
8console.log('walk away');

Calling an async function is a NORMAL call: order() pushes onto the stack and starts executing synchronously.

1 / 7

Call stack

script
order()

Web APIs — browser land

The event loop — is the call stack empty? → drain the microtask queue first → then take one callback.

Microtask queue — priority

Callback queue

Console

Fig. — async/await, unmasked · step 1 of 7

← → step · space play · 123 level