Environment Variable Secret Pattern (.env file) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching environment variable secret pattern (.env file), ported and verified for JavaScript. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. 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

// Environment Variable Secret Pattern (.env file)
// ReDoS-safe | RegexVault — Security > Secrets & Config

const environmentVariableSecretPatternEnvFileRegex = /^((?:[A-Z_]+)?(?:PASSWORD|SECRET|TOKEN|KEY|CREDENTIAL|AUTH|API)[A-Z_]*)=([^\r\n#]{8,})$/m;

function validateEnvironmentVariableSecretPatternEnvFile(input: string): boolean {
  return environmentVariableSecretPatternEnvFileRegex.test(input);
}

// Example
console.log(validateEnvironmentVariableSecretPatternEnvFile("DATABASE_PASSWORD=mySecretPassword123")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Security > Secrets & Config 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

.env files should never be committed to version control. Use .gitignore to exclude .env files. The pattern uses multiline mode to match line-by-line. Capture group 1=key name, group 2=value. Value must be at least 8 chars to reduce false positives.