Fixing Webpack's JavaScript Source Maps: Generate TypeScript Maps Instead!

Struggling with Webpack generating JavaScript source maps instead of TypeScript? Discover how a simple configuration could fix your source mapping issues.
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Fixing Webpack's JavaScript Source Maps: Generate TypeScript Maps Instead!

If you've been developing a TypeScript application using Webpack, you may have encountered a frustrating issue: while trying to generate source maps, you end up with maps for JavaScript instead of your original TypeScript files. This can lead to confusion while debugging, as you won't be able to match the source maps with your TypeScript code. In this post, we’ll explore the problem and a straightforward solution to ensure Webpack generates the correct TypeScript source maps.

The Problem

Imagine you've set up a TypeScript project with Angular 11 and Webpack, and everything seems to be running smoothly. You’ve configured Webpack to generate source maps, and although it successfully creates them, they reference the compiled JavaScript code rather than the TypeScript source. This mismatch can cause significant headaches when debugging your application.

Here's a summary of the key details surrounding the issue:

Webpack Version: 4.44.2

TypeScript Version: 4.0.5

Angular Version: 11.0.6

Error Context

The problem arises during the build process when Webpack doesn't properly resolve the TypeScript files for source mapping. It appears that there’s a configuration oversight in the Webpack setup that’s leading to this issue.

The Solution

A Simple Configuration Change

Fortunately, the solution to this problem is not overly complex. The main adjustment needed lies in the Webpack configuration file. By adding the resolve section to your configuration, along with specifying the file extensions, you can guide Webpack to correctly include TypeScript files for source mapping.

Here's the specific line of code you should add to your Webpack configuration:

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Where to Add This Configuration

Locate the main module export function.

Add the resolve section, ideally before the module rules section.

Save the changes and rebuild your project.

Understanding the Change

By adding the resolve configuration with the specified extensions, you instruct Webpack to recognize both TypeScript (.ts) and JavaScript (.js) files when resolving modules during bundling. This allows Webpack to properly associate the source maps with the original TypeScript files instead of with the JavaScript output.

Additional Recommendations

Consider Webpack’s Mode: If you are running in a production environment, ensure that the devtool property is correctly set to a suitable source map option.

Debugging Further: If issues persist after these changes, double-check other parts of your configuration and ensure there aren’t any conflicts with loaders, plugins, or other settings.

Conclusion

By following the above steps and making this small yet impactful change to your Webpack configuration, you should be able to generate accurate TypeScript source maps for your Angular projects. This adjustment will enhance your debugging experience, enabling you to effectively trace errors back to your original TypeScript code. Don’t let misconfigured source maps hinder your development process; implement this fix today!