How do you wait for a return from a function before moving on in node

Question

I'm new to Node so I'm struggling with this. The script runs as if its "skipping" the bitx.getTicker function inside the while loop. I did some research on asynchronous functions in Node and I just cant seem to get it working on my code. I'm trying to write a crypto-bot with bitx. I tried the .then() method as well and it just keeps on "skipping" the bitx.getTicker function. If I remove the async(from line 1), let tick = await``(from line 5) and the while``` loop it works as intended but just once. I need it to run constantly to check new asking price so once wont work. Thanks in advance.

async function get_ticker(){ let BitX = require('../lib/BitX') while(true){ let bitx = new BitX(key, secret) let tick = await bitx.getTicker(function (err, ticker) { // sends ticker object to another function to get values get_info(ticker) }) console.log(i) i = i + 1 } }

UPDATE I used a promise and I see it pending but I cant access the ticker variable inside the bitx.getTicker function. How can I access it?

function get_ticker() { let BitX = require('../lib/BitX') const promise = new Promise((resolve, reject) => { let bitx = new BitX(key, secret) bitx.getTicker(function (err, ticker) { resolve(ticker) }) }) return promise.resolve } var result = get_ticker() console.log(result)

It keeps skipping because you have passed a callback to getTicker method. You can either use callback-based API or use promises if BitX provides a method that returns a promise. With your current code, there's no point in awaiting bite.getTicker. If bite.getTicker doesn't return a promise, you can promising it using node's built-in util module. — Yousaf
– Yousaf, Commented Aug 20, 2022 at 12:27
Thanks for your answer @Yousaf. I updated my question and it looks like it works fine now but how would you access the ticker variable? I tried it in the above and I see the promise pending but I cant access the variable? — Dylan
– Dylan, Commented Aug 20, 2022 at 12:48

CherryDT · Accepted Answer · 2022-08-20 13:34:46Z

It seems like your BitX library doesn't have a promise interface but is callback-based, so you need to promisify it:

const { promisify } = require('util') async function get_ticker(){ let BitX = require('../lib/BitX') while(true){ let bitx = new BitX(key, secret) let tick = await promisify(bitx.getTicker).call(bitx) get_info(tick) console.log(i) i = i + 1 } }

It would be more performant to create the client only once though:

const { promisify } = require('util') const BitX = require('../lib/BitX') const bitx = new BitX(key, secret) const getBitxTicker = promisify(bitx.getTicker).bind(bitx) async function get_ticker(){ while(true){ const tick = await getBitxTicker() get_info(tick) console.log(i) i = i + 1 } }

(Note that I used bind instead of call now for binding the bitx instance, because we don't immediately call it now.)

Thanks for the reply @CherryDT. It works perfect if I pass tick`` to the get_info``` function. I just want to ask, if I only created the client once, wont I receive the same values the whole time? I want to receive live values, that's why I thought to create it repeatedly. Please let me know. Thanks :)
You still ask the (same) client every time to check the values by calling its getTicker function so you won't receive the same.

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