Unix Absolute Path Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching unix absolute path, 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

// Unix Absolute Path
// ReDoS-safe | RegexVault — Dev & Systems > File Paths

const unixAbsolutePathRegex = /^\\/(?!.*\.\.\\/)(?!.*\s)(?!.*\n)(?:[^\\/\0]+\\/?)*$/;

function validateUnixAbsolutePath(input: string): boolean {
  return unixAbsolutePathRegex.test(input);
}

// Example
console.log(validateUnixAbsolutePath("/")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > File Paths 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

Intentionally restrictive: no spaces, control characters, or path traversal sequences. Use for validated inputs, not for parsing arbitrary filesystem paths which can contain almost any character except NUL.