HTTP Status Code Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching http status code, 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

// HTTP Status Code
// ReDoS-safe | RegexVault — Web & Network > HTTP

const httpStatusCodeRegex = /^([1-5][0-9]{2})(?:\s+(.+))?$/;

function validateHttpStatusCode(input: string): boolean {
  return httpStatusCodeRegex.test(input);
}

// Example
console.log(validateHttpStatusCode("200")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > HTTP 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

Capture group 1 is the status code, group 2 is the optional reason phrase. Note: 6xx and above are not standard. Use application logic to further validate that specific codes are supported (e.g., 418 is valid but 491 is not officially defined).