Rule Details

Source maps are a critical bridge between the minified code that runs in a user's browser and the original source code that developers write. Without them, debugging production errors is nearly impossible.

Code Examples

Generating Source Maps (Webpack)

// ✅ Good: Generate a source map that's easy to debug
module.exports = {
  devtool: 'source-map', // Options vary by build tool and environment
};

Source Map Link (Minified File)

// at the end of your app.min.js
//# sourceMappingURL=app.min.js.map

Excluding Source Maps from Public Production (Vite)

// ✅ Good: Generate hidden source maps for external error trackers
export default {
  build: {
    sourcemap: 'hidden', // Maps are generated but not linked in the JS
  },
};

Why It Matters

• Easier Debugging: See the exact line and column in your original code where an error occurred.
• Accurate Stack Traces: Error tracking services like Sentry or LogRocket use source maps to provide meaningful error reports.
• Improved Monitoring: Detailed production logs allow for faster bug identification and resolution.
• Maintain Performance: You get all the benefits of minification and obfuscation while still retaining the ability to debug your code.

Best Practices

✅ Always Generate in Build: Ensure source maps are a standard part of your build process. ✅ Secure Your Maps: Don't upload source maps to your public web server if you want to protect your source code; upload them to your error tracking tool instead. ✅ Use hidden-source-map: This is a great way to generate maps without making them publicly available in the browser's developer tools. ✅ Test Your Integration: Manually verify that your error tracker is correctly de-minifying stack traces.

Tools & Validation

Keep source-map verification tied to the real error-reporting path, because Sentry’s source map docs (opens in new tab) or your tracker’s upload flow matter more than whether the map file exists locally.

• Sentry Source Map Documentation (opens in new tab)
• Webpack devtool documentation is useful when you need to choose the right source-map mode for a build.
• Vite build options document when maps are hidden, linked, or omitted.
• Browser DevTools (Sources tab -> look for your original files)

Standards

• Use web.dev: Learn Performance as the standard for measuring the final production behavior, not just local synthetic output.
• Use Chrome Developers: Lighthouse overview as the standard for measuring the final production behavior, not just local synthetic output.

Verification

Automated Checks

• Measure the affected page or flow in Lighthouse, PageSpeed Insights, or DevTools and confirm the targeted metric improves.
• Inspect the network waterfall or performance timeline to confirm the intended resource or execution change actually took effect.

Manual Checks

• Verify the change on a throttled mobile profile, not just local desktop.
• If this rule maps to a budget or Web Vital, confirm the page now stays within that threshold.