Cookie Name=Value Pair Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching cookie name=value pair, 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

// Cookie Name=Value Pair
// ReDoS-safe | RegexVault — Web & Network > HTTP

const cookieNamevaluePairRegex = /^([!#-'*-+\-.0-9A-Z^-z|~]+)=([\x21\x23-\x2B\x2D-\x3A\x3C-\x5B\x5D-\x7E]*)$/;

function validateCookieNamevaluePair(input: string): boolean {
  return cookieNamevaluePairRegex.test(input);
}

// Example
console.log(validateCookieNamevaluePair("session=abc123")); // 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

Cookie names cannot contain separators, whitespace, or control characters. Values cannot contain whitespace, comma, semicolon, or backslash. Many cookies in practice use base64 — the character set is compatible.