Git Branch Name Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching git branch name, 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

// Git Branch Name
// ReDoS-safe | RegexVault — Dev & Systems > Git

const gitBranchNameRegex = /^(?!HEAD$|FETCH_HEAD$|ORIG_HEAD$|MERGE_HEAD$)(?!.*\.\.)(?!.*\s)[a-zA-Z0-9][a-zA-Z0-9._\-\/]{0,249}$/;

function validateGitBranchName(input: string): boolean {
  return gitBranchNameRegex.test(input);
}

// Example
console.log(validateGitBranchName("main")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Git 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

Git branch names cannot contain .., whitespace, control characters, or reserved names (HEAD, FETCH_HEAD). Lookaheads enforce these constraints. Go's RE2 does not support lookaheads — validate separately.