JavaScript Error Tracking for Websites — Find the Errors That Actually Cost You Conversions

Open the console on almost any production website and you'll see errors. Most are harmless—a failed analytics beacon, a browser extension, a deprecated API warning. A few are silently breaking checkouts, signups, and forms. The challenge isn't collecting errors; it's knowing which ones matter.

Table of Contents

1. Why Website Errors Go Unnoticed
2. How Error Tracking Works
3. Prioritize by Affected Sessions
4. Connect Errors to Replays
5. Noise to Ignore
6. A Weekly Error Review
7. Key Takeaways

Why Website Errors Go Unnoticed

• Users rarely report errors—they just leave.
• Errors may occur only on certain browsers or devices.
• Third-party scripts fail without your code changing.
• Marketing sites often have no monitoring at all.

How Error Tracking Works

A tracking script listens for uncaught exceptions and unhandled promise rejections in visitors' browsers. Errors are grouped by message and stack signature, so ten thousand occurrences of the same bug become one group. DeepSync includes JavaScript error tracking on every plan, including Free.

Prioritize by Affected Sessions

Rank error groups by:

1. Affected sessions — how many visitors hit it
2. Page — is it on a conversion path (checkout, signup, pricing)?
3. Trend — did it start after a deploy?
4. Conversion impact — do sessions with this error convert less?

Connect Errors to Replays

An error message tells you what threw. A replay tells you what the user was doing and whether it broke their experience. From each error group, open a session where it occurred and check:

• Did the UI break visibly?
• Did the user retry (rage click) or leave?
• Which network request preceded it?

This is how you separate "harmless noise" from "silently breaking checkout." Full workflow: reproduce bugs with session replay.

Noise to Ignore

• Browser extension errors (stack traces from extension URLs)
• "Script error." from cross-origin scripts without CORS headers (add crossorigin attributes to see details)
• ResizeObserver loop warnings
• Ad blocker-blocked third-party scripts (unless they power something critical)

A Weekly Error Review

1. Sort error groups by affected sessions.
2. Filter to key pages (checkout, signup, pricing).
3. Open replays for the top 3 new groups.
4. File tickets with replay links.
5. After fixes deploy, confirm the group stops occurring.

Teams on Business plans can let Pulse flag error surges automatically in its daily brief.

Key Takeaways

• Most console errors are noise; a few silently cost conversions.
• Rank by affected sessions and page importance.
• Open a replay for every important error group.
• Review weekly and after every deploy.

Conclusion

Errors your users hit but never report are costing you money right now. Start tracking them and watch the replays.

Start free.