URL Scheme Extraction Regex for JavaScript

What this pattern does

This page provides a well-structured, multi-part regular expression for matching url scheme extraction, 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

// URL Scheme Extraction
// ReDoS-safe | RegexVault — Web & Network > URL

const urlSchemeExtractionRegex = /^([a-zA-Z][a-zA-Z0-9+\-.]{0,20}):\/\//;

function validateUrlSchemeExtraction(input: string): boolean {
  return urlSchemeExtractionRegex.test(input);
}

// Example
console.log(validateUrlSchemeExtraction("https://example.com")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > URL 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 contains the scheme. Scheme syntax per RFC 3986: starts with a letter, followed by letters/digits/+/-/. The length cap of 20 prevents runaway matching on non-URL strings.