You have successfully deployed your application on Vercel, and you can see the index.html, js, and css files online. However, you are facing an issue, and your app is not working as expected. This article will guide you through the process of troubleshooting common deployment issues on Vercel, specifically focusing on JavaScript (JS), Cascading Style Sheets (CSS), and asset folders such as dist and assets.
1. Check the Console Logs
The first step in identifying the issue is to check the console logs in the browser's developer tools. This will help you understand if there are any errors related to JS, CSS, or assets. To access the console logs, right-click on your webpage, select "Inspect," and navigate to the "Console" tab.
2. Verify JavaScript Files
Verify that your JavaScript files are being loaded correctly. You can check this by looking at the network tab in the developer tools and ensuring that the JS files are being requested and received without any errors. If there are any issues, double-check your file paths and ensure they are correct.
// Example of a correct JavaScript import
import React from 'react';
import ReactDOM from 'react-dom';
ReactDOM.render(Hello, World!
, document.getElementById('root'));
3. Examine CSS Styles
Next, examine your CSS styles. Ensure that the styles are being applied to the elements as intended. Similar to the network tab for JS files, check the "Network" tab for CSS files. Verify that there are no errors related to CSS file paths.
/* Example of a correct CSS rule */
h1 {
color: blue;
}
4. Handle Asset Folders
Vercel might not serve files from custom asset folders such as dist and assets by default. To handle this, you can configure a Vercel "output" directory for your project. For instance, if you want to serve files from the dist folder, you can do this by adding a vercel.json file to the root directory of your project:
{
"version": 2,
"outputDirectory": "dist"
}
This will inform Vercel to serve files from the dist folder when deploying your application.
5. Verify Asset References
After you have configured the output directory, ensure that all asset references are correct. If your assets are located in a subdirectory, include the subdirectory name while referencing the assets. For example:
<img src="assets/my-image.png" alt="My Image">
6. Utilize Environment Variables
Environment variables can be useful when referencing assets, especially when building for production. You can define environment variables in your Vercel dashboard or by using a .env file locally. For example:
// .env file
ASSET_URL=https://example.com/assets
7. Additional Considerations
- CORS (Cross-Origin Resource Sharing): Check if your assets are being blocked due to CORS issues. Ensure that your server is configured to allow cross-origin requests from Vercel.
- Cache Busting: When deploying updated assets, ensure that cache busting is enabled, so that users receive the most recent version of your assets instead of being served stale files from their cache.
Summary
- Check the console logs for errors related to JS, CSS, or assets
- Verify JavaScript files have the correct file paths
- Examine CSS styles for proper application
- Handle asset folders and define the 'outputDirectory' in Vercel configuration
- Verify asset references, including subdirectories if necessary
- Utilize environment variables for assets, especially in production builds
- Consider CORS and cache busting issues