Cron Expression (Standard 5-Field) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching cron expression (standard 5-field), 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

// Cron Expression (Standard 5-Field)
// ReDoS-safe | RegexVault — Dev & Systems > Cron

const cronExpressionStandard5fieldRegex = /^(\*|[0-9]|[1-5][0-9])(?:[-\/,](?:[0-9]|[1-5][0-9]))? (\*|[01]?[0-9]|2[0-3])(?:[-\/,](?:[01]?[0-9]|2[0-3]))? (\*|[1-9]|[12][0-9]|3[01])(?:[-\/,](?:[1-9]|[12][0-9]|3[01]))? (\*|[1-9]|1[0-2])(?:[-\/,](?:[1-9]|1[0-2]))? (\*|[0-7])(?:[-\/,][0-7])?$/;

function validateCronExpressionStandard5field(input: string): boolean {
  return cronExpressionStandard5fieldRegex.test(input);
}

// Example
console.log(validateCronExpressionStandard5field("* * * * *")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Cron 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

5 space-separated fields: minute (0-59), hour (0-23), day-of-month (1-31), month (1-12), day-of-week (0-7). Both 0 and 7 are Sunday. Does not catch logically impossible date combinations. Use a dedicated cron library for full semantic validation.