How to setTimeout on async await call node - node.js

Question

How can I add a setTimeout to my async await function call?
I have
request = await getProduct(productids[i]);
where
const getProduct = async productid => {
return requestPromise(url + productid);
};
I've tried
request = await setTimeout((getProduct(productids[i])), 5000);
and got the error TypeError: "callback" argument must be a function which makes sense. The request is inside of a loop which is making me hit the rate limit on an api call.
exports.getProducts = async (req, res) => {
let request;
for (let i = 0; i <= productids.length - 1; i++) {
request = await getProduct(productids[i]);
//I want to wait 5 seconds before making another call in this loop!
}
};

Answer 1

You can use a simple little function that returns a promise that resolves after a delay:
function delay(t, val) {
return new Promise(function(resolve) {
setTimeout(function() {
resolve(val);
}, t);
});
}
// or a more condensed version
const delay = (t, val) => new Promise(resolve => setTimeout(resolve, t, val));
And, then await that inside your loop:
exports.getProducts = async (req, res) => {
let request;
for (let id of productids) {
request = await getProduct(id);
await delay(5000);
}
};
Note: I also switched your for loop to use for/of which is not required, but is a bit cleaner than what you had.
Or, in modern versions of nodejs, you can use timersPromises.setTimeout() which is a built-in timer that returns a promise (as of nodejs v15):
const setTimeoutP = require('timers/promises').setTimeout;
exports.getProducts = async (req, res) => {
let request;
for (let id of productids) {
request = await getProduct(id);
await setTimeoutP(5000);
}
};

Answer 2

Actually, I have a pretty standard chunk of code that I use to do that:
function PromiseTimeout(delayms) {
return new Promise(function (resolve, reject) {
setTimeout(resolve, delayms);
});
}
Usage:
await PromiseTimeout(1000);
If you're using Bluebird promises, then it's built in as Promise.timeout.
More to your problem: Have you checked API docs? Some APIs tell you how much you have to wait before next request. Or allow downloading data in larger bulk.

Answer 3

As of node v15 you can use the Timers Promises API:
const timersPromises = require('timers/promises');
async function test() {
await timersPromises.setTimeout(1000);
}
test();
Note that this feature is experimental and may change in future versions.

Answer 4

Since Node 15 and above, there is the new Timers Promises API that let you to avoid to build the wrapping:
import {
setTimeout,
setImmediate,
setInterval,
} from 'timers/promises';
console.log('before')
await setTimeout(1000)
console.log('after 1 sec')
So your issues you could write it with async iterator:
import {
setTimeout
} from 'timers/promises'
async function getProducts (req, res) {
const productids = [1, 2, 3]
for await (const product of processData(productids)) {
console.log(product)
}
}
async function * processData (productids) {
while (productids.length > 0) {
const id = productids.pop()
const product = { id }
yield product
await setTimeout(5000)
}
}
getProducts()

Answer 5

I have done api delay test as below.
It is possible to delay it as if by hanging setTimeout.
sleep(ms) {
const wakeUpTime = Date.now() + ms;
while (Date.now() < wakeUpTime) {}
}
callAPI = async() => {
... // Execute api logic
await this.sleep(2147483647);
... // Execute api logic
}
await callAPI();