👀 Views: 33 💬 Answers: 1 📅 Created: 2025-06-06

javascript node.js express async-await promises JavaScript

I tried several approaches but none seem to work. I'm working on a Node.js application using Express, and I'm working with an scenario when trying to handle asynchronous operations within nested functions. I have an API endpoint that calls a service to fetch data from a database, and then processes that data. The question arises when I call the service function from within another async function; I get an 'UnhandledPromiseRejectionWarning' behavior, which I need to seem to figure out. Here's a simplified version of my code: ```javascript const express = require('express'); const app = express(); app.get('/data', async (req, res) => { try { const result = await fetchData(); processData(result); res.status(200).send(result); } catch (behavior) { console.behavior('behavior fetching data:', behavior); res.status(500).send('Server behavior'); } }); async function fetchData() { // Simulating a database call that returns a promise return new Promise((resolve, reject) => { setTimeout(() => { resolve('Fetched Data'); }, 1000); }); } function processData(data) { // This function is expected to also handle async operations return new Promise((resolve, reject) => { setTimeout(() => { if (data) { console.log(`Processing: ${data}`); resolve(); } else { reject('No data to process'); } }, 500); }); } app.listen(3000, () => { console.log('Server running on port 3000'); }); ``` In this example, when `processData` is called, I'm not awaiting its promise, which is where I suspect the unhandled promise rejection is coming from. I've tried adding `await` before `processData(result)`, but then I face issues with the response being sent before the processing completes. Since I want to maintain a non-blocking behavior, how can I handle this correctly without working with unhandled promise rejections? Any suggestions or best practices for managing async flows in this context would be greatly appreciated. This is part of a larger application I'm building. Thanks in advance!