Error Handling Checker

Evaluate JavaScript and HTML for proper error handling patterns. Checks for try-catch blocks, promise rejection handling, input validation, global error listeners, user-facing error messages, and more.

Drop a .html or .js file here or browse

HTML / JavaScript to check:

Try examples:

Well handled No error handling Partial handling

How It Works

This tool parses your HTML and JavaScript to evaluate error handling quality across multiple categories. All processing happens entirely in your browser — no data is sent to any server.

Checklist Categories

Try-Catch — Presence of try...catch blocks around risky operations like JSON parsing, DOM access, and API calls
Promise Handling — .catch() on promises, async/await with try-catch, and unhandledrejection listeners
Global Handlers — window.onerror or addEventListener("error") for uncaught exceptions
Input Validation — Form validation attributes, type checks, and sanitization before processing user input

Network Errors — Fetch/XHR error handling, response status checks, timeout handling, and retry patterns
User Feedback — User-facing error messages, loading states, and graceful fallbacks instead of silent failures
Best Practices — Console error logging, specific error types, avoiding empty catch blocks, and error context

Scoring

Each check is weighted equally. Passes score full points, warnings half, and failures zero. The final percentage determines the grade:

Score	Grade
80 – 100%	Robust error handling
50 – 79%	Needs improvement
0 – 49%	Poor error handling

Tip: This checker analyzes static source code patterns. For a complete audit, also test with browser DevTools open and network throttling enabled to catch runtime errors.

Related Utils

HTML Validator JSON Validator CSS Validator Dark Mode Checker Responsive Checker

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