Log Level Detection Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching log level detection, ported and verified for JavaScript. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your JavaScript project — whether you're validating in an Express middleware, a Next.js API route, or a client-side form.

Javascript Implementation

// Log Level Detection
// ReDoS-safe | RegexVault — Dev & Systems > Log Parsing

const logLevelDetectionRegex = /\b(TRACE|DEBUG|INFO|WARN(?:ING)?|ERROR|FATAL|CRITICAL|NOTICE|SEVERE)\b/i;

function validateLogLevelDetection(input: string): boolean {
  return logLevelDetectionRegex.test(input);
}

// Example
console.log(validateLogLevelDetection("INFO: server started")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Log Parsing category and carries a ReDoS-safe certification. That matters for JavaScript developers because especially critical in long-running Node.js event loops where a ReDoS vulnerability can block the entire process. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

The \b word boundaries prevent partial matches (INFORMATION matching as INFO). Capture group 1 contains the matched level. Normalize to a canonical set for cross-framework analysis.