Handling CORS Issues When Integrating HTML Forms with a Third-Party API
I'm updating my dependencies and I'm getting frustrated with Working on a project where I need to connect a frontend built in HTML and JavaScript to a third-party API that requires CORS (Cross-Origin Resource Sharing) headers. The API supports only GET and POST requests, and I want to ensure that my HTML form can submit data correctly. Initially, I set up a simple HTML form: ```html <form id="myForm"> <input type="text" name="username" required /> <input type="submit" value="Submit" /> </form> ``` In my JavaScript, I’m using Fetch API to send the form data: ```javascript document.getElementById('myForm').addEventListener('submit', function(event) { event.preventDefault(); const formData = new FormData(this); fetch('https://api.example.com/submit', { method: 'POST', body: formData, headers: { 'Accept': 'application/json', 'Content-Type': 'application/x-www-form-urlencoded', } }) .then(response => response.json()) .then(data => console.log(data)) .catch(error => console.error('Error:', error)); }); ``` Despite following what I thought were best practices, I've run into a couple of issues. First, the browser console indicates "No 'Access-Control-Allow-Origin' header is present on the requested resource." I know that this means I need the API to permit my domain, but since it’s a third-party service, I cannot control that. As a workaround, I considered setting up a proxy server to handle the CORS headers. I found an example using Express: ```javascript const express = require('express'); const cors = require('cors'); const app = express(); app.use(cors()); app.use(express.json()); app.post('/proxy', (req, res) => { fetch('https://api.example.com/submit', { method: 'POST', body: req.body, }) .then(apiResponse => apiResponse.json()) .then(apiData => res.json(apiData)); }); ``` After implementing the proxy, I modified the fetch call in the frontend to point to my server instead: ```javascript fetch('/proxy', { ... }) ``` While this solution seems to work during local testing, I’m concerned about deployment. Is there a more elegant or secure way to handle CORS without having to deploy a proxy server? Any suggestions for best practices that would help ensure smooth integration with the third-party API would be greatly appreciated. My team is using Javascript for this desktop app. What's the best practice here? This is part of a larger desktop app I'm building. Any pointers in the right direction?