Combination of async function + await + setTimeout

Your sleep function does not work because setTimeout does not (yet?) return a promise that could be awaited. You will need to promisify it manually:

function timeout(ms) {    return new Promise(resolve => setTimeout(resolve, ms));}async function sleep(fn, ...args) {    await timeout(3000);    return fn(...args);}

Btw, to slow down your loop you probably don't want to use a sleep function that takes a callback and defers it like this. I recommend:

while (goOn) {  // other code  var [parents] = await Promise.all([      listFiles(nextPageToken).then(requestParents),      timeout(5000)  ]);  // other code}

which lets the computation of parents take at least 5 seconds.

The quick one-liner, inline way

 await new Promise(resolve => setTimeout(resolve, 1000));

Since Node 7.6, you can combine the functions promisify function from the utils module with setTimeout() .

Node.js

const sleep = require('util').promisify(setTimeout)

Javascript

const sleep = m => new Promise(r => setTimeout(r, m))

Usage

(async () => {    console.time("Slept for")    await sleep(3000)    console.timeEnd("Slept for")})()