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Browser Checks

Browser checks use a real headless browser to load your pages and detect JavaScript errors that could impact your customers.

How It Works​

Pulsar uses a headless Chrome browser to:

  1. Navigate to your page
  2. Wait for the page to fully load
  3. Capture any JavaScript errors
  4. Report console errors and uncaught exceptions

What Gets Captured​

Console Errors​

Any console.error() calls are captured and reported:

// This will be captured
console.error("Failed to load product images");

Uncaught Exceptions​

JavaScript exceptions that aren't handled are detected:

// This will trigger an alert
throw new Error("Payment gateway unavailable");

Network Errors​

Failed network requests that result in JavaScript errors are captured.

Console Warnings (opt-in)​

Third-party services often announce their own degradation only via console.warn — for example, a consent manager CDN that has exhausted its plan quota logs a warning while serving an HTTP 200 stub:

// The only visible symptom of a broken consent setup
console.warn('[CCM19] Quota exceeded');

Enable Capture Console Warnings on a browser-checked page to record these. Captured warnings are advisory by default — they show up on the check but never trigger an alert on their own.

To alert on a specific warning, add a warn alert pattern (in the page's error patterns, type Warn Alert). A captured warning matching the pattern degrades the check and sends an alert naming the warning:

Warn alert pattern: [CCM19] Quota exceeded
Be specific with warn alert patterns

Use a distinctive substring, not something generic like quota exceeded — browsers emit benign QuotaExceededError warnings for localStorage (e.g. Safari private mode), which would false-positive.

Configuration​

Wait for Selector​

Specify a CSS selector to wait for before checking for errors:

Wait for: #main-content

This ensures the page is fully loaded before capturing errors.

Viewport Size​

Set the browser viewport size (default: 1920x1080):

ViewportUse Case
1920x1080Desktop
1366x768Laptop
375x667Mobile

Error Patterns​

Configure patterns to ignore known, non-critical errors:

# Ignore third-party tracking errors
.*gtm\.js.*
.*analytics.*

# Ignore deprecation warnings
.*deprecated.*

Best Practices​

  1. Start with default settings - Enable browser checks and monitor for a few days
  2. Add error patterns gradually - Only ignore errors you've investigated
  3. Monitor checkout pages - JavaScript errors here directly impact conversions
  4. Check mobile views - Some errors only occur on specific viewports

Limitations​

  • Browser checks are more resource-intensive than HTTP checks
  • Maximum page load time is 30 seconds
  • Some third-party scripts may cause false positives