Level 1 - JavaScript error rate scorecard rule

JavaScript error rate measures the percentage of your browser applications that experience JavaScript errors, which can break user functionality and create poor user experiences. This scorecard rule helps you identify and prioritize fixing frontend issues that directly impact customer satisfaction.

About this scorecard rule

This JavaScript error rate rule is part of Level 1 (Reactive) in the digital experience maturity model. It evaluates whether your browser applications have unresolved JavaScript errors that could be affecting users.

Why this matters: JavaScript errors can break critical user functionality like forms, navigation, payments, or interactive features. Users encountering broken functionality often abandon tasks, leading to lost conversions and negative brand perception.

How this rule works

This rule evaluates the percentage of browser entities (applications monitored by New Relic Browser) that exhibit JavaScript errors. It identifies applications where users may be experiencing broken functionality due to frontend code issues.

Understanding your score

• Pass (Green): Low percentage of browser applications have JavaScript errors affecting users
• Fail (Red): High percentage of browser applications have unresolved JavaScript errors
• Target: Minimize JavaScript errors across all browser applications, especially those with high user traffic

What this means:

• Passing score: Your frontend applications provide reliable user experiences with minimal broken functionality
• Failing score: Users may be encountering broken features, forms, or interactions that could impact satisfaction and conversions

How to reduce JavaScript error rates

If your score shows high JavaScript error rates, follow these steps to identify and resolve frontend issues:

1. Analyze error patterns in Error Inbox

1. Access Error Inbox: Navigate to New Relic's Error Inbox to see all JavaScript errors across your applications
2. Identify high-impact errors: Focus on errors affecting the most users or critical user journeys
3. Group similar errors: Look for patterns in error messages, affected pages, or user segments
4. Prioritize by business impact: Address errors on high-traffic pages or conversion-critical flows first

2. Categorize and triage errors

Critical errors (fix immediately):

• Payment processing failures
• User authentication issues
• Data submission problems
• Navigation or routing failures

High-priority errors (fix within sprint):

• Form validation failures
• Search functionality issues
• User interaction problems
• Content loading failures

Medium-priority errors (fix in upcoming releases):

• Minor UI glitches
• Non-critical feature failures
• Cosmetic or styling issues
• Edge case scenarios

3. Implement systematic error resolution

Reproduce and diagnose:

• Use stack traces: Examine error details to understand what code is failing
• Check browser compatibility: Verify errors aren't browser-specific issues
• Test user scenarios: Reproduce the user actions that trigger errors
• Review recent deployments: Check if errors correlate with recent code changes

Fix root causes:

• Null/undefined checks: Add proper error handling for missing data
• API error handling: Implement graceful fallbacks for failed network requests
• Input validation: Ensure forms handle edge cases and invalid input
• Resource loading: Add error handling for missing images, scripts, or stylesheets

4. Establish error prevention practices

Implement better error handling:

• Try-catch blocks: Wrap risky operations in proper error handling
• Default values: Provide fallbacks for missing or invalid data
• Graceful degradation: Ensure core functionality works even when features fail
• User-friendly messages: Display helpful error messages instead of technical details

Improve development practices:

• Code reviews: Focus on error handling during peer reviews
• Testing strategies: Include error scenarios in unit and integration tests
• Staging environment: Test thoroughly before production releases
• Monitoring integration: Add error tracking to development and staging environments

Measuring improvement

Track these metrics to verify your JavaScript error reduction efforts:

• Error rate reduction: Decreasing percentage of applications with JavaScript errors
• User impact metrics: Improved conversion rates, reduced bounce rates, higher user satisfaction
• Error resolution time: Faster identification and fixing of JavaScript issues
• Error recurrence: Fewer repeated errors after fixes are deployed

Common JavaScript error scenarios

Third-party script failures:

• Problem: External libraries or widgets cause errors when they fail to load or have issues
• Solution: Implement error boundaries, use fallbacks, and monitor third-party dependencies

Browser compatibility issues:

• Problem: Code works in some browsers but fails in others
• Solution: Test across browsers, use polyfills, and implement progressive enhancement

Network and API failures:

• Problem: JavaScript errors when network requests fail or return unexpected data
• Solution: Add proper error handling for API calls, implement retry logic, and provide user feedback

User input edge cases:

• Problem: Forms or interactions break with unexpected user input
• Solution: Implement comprehensive input validation and sanitization

Advanced error management strategies

Error tracking automation

• Automated alerting: Set up alerts for new or frequent JavaScript errors
• Error grouping: Use intelligent grouping to avoid alert fatigue
• Impact scoring: Prioritize errors based on user impact and frequency

Integration with development workflow

• CI/CD integration: Block deployments if critical errors are detected
• Performance budgets: Set error rate thresholds as deployment gates
• Error attribution: Connect errors to specific deployments or feature releases

User experience focus

• Real user monitoring: Track how errors affect actual user behavior
• Conversion impact: Measure how error rates correlate with business metrics
• User journey analysis: Understand where in the user flow errors occur most frequently

Important considerations

• Prioritize by user impact: Focus first on errors affecting the most users or critical business functions
• Balance perfection with practicality: Some errors may be acceptable if they don't significantly impact user experience
• Consider business context: High-traffic applications may need lower error tolerance than internal tools
• Monitor post-deployment: Ensure fixes don't introduce new errors

Next steps

1. Immediate action: Review Error Inbox and identify the highest-impact JavaScript errors affecting users
2. Process improvement: Establish regular error triage meetings and resolution workflows
3. Prevention focus: Implement better error handling practices in development processes
4. Advance monitoring: Move toward proactive error prevention and user experience optimization
5. Progress to Level 2: Once JavaScript errors are under control, focus on Core Web Vitals optimization

For detailed guidance on JavaScript error monitoring and resolution, see our Browser monitoring documentation and Error Inbox guide.