Lot Size / Quantity (Financial) Regex for JavaScript

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching lot size / quantity (financial), ported and verified for JavaScript. Financial data validation has zero tolerance for false negatives — a missed invalid entry can corrupt downstream calculations. 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

// Lot Size / Quantity (Financial)
// ReDoS-safe | RegexVault — Finance > Financial Formats

const lotSizeQuantityFinancialRegex = /^(?:(?!0[0-9])[0-9]+(?:\.[0-9]*[1-9])?|0\.[0-9]*[1-9])$/;

function validateLotSizeQuantityFinancial(input: string): boolean {
  return lotSizeQuantityFinancialRegex.test(input);
}

// Example
console.log(validateLotSizeQuantityFinancial("100")); // true

Test Cases

When to use this pattern

This pattern is drawn from the Finance > Financial Formats 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

Covers everything from stock lots (integer) to fractional crypto amounts (8 decimal places for Bitcoin). Rejects scientific notation (1e5) — always expand to decimal form for financial quantities.