SemVer Pre-Release Identifier Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching semver pre-release identifier, 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

// SemVer Pre-Release Identifier
// ReDoS-safe | RegexVault — Dev & Systems > SemVer

const semverPrereleaseIdentifierRegex = /^(?:0|[1-9][0-9]*|[0-9]*[a-zA-Z][a-zA-Z0-9\-]*)(?:\.(?:0|[1-9][0-9]*|[0-9]*[a-zA-Z][a-zA-Z0-9\-]*))*$/;

function validateSemverPrereleaseIdentifier(input: string): boolean {
  return semverPrereleaseIdentifierRegex.test(input);
}

// Example
console.log(validateSemverPrereleaseIdentifier("alpha")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > SemVer 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

Numeric identifiers must not have leading zeros (01 is invalid). Alphanumeric identifiers have lower precedence than numeric ones in version comparison.