JavaScript pro tip:

Use Intl.NumberFormat method instead of formatting numbers manually. It’s a built-in API that handles locale and formatting rules for you.

Example:

const amount = 1234567.89;

const usd = new Intl.NumberFormat("en-US", { style: "currency", currency: "USD" }).format(amount);
const eur = new Intl.NumberFormat("de-DE", { style: "currency", currency: "EUR" }).format(amount);
const jpy = new Intl.NumberFormat("ja-JP", { style: "currency", currency: "JPY" }).format(amount);

console.log(usd); // $1,234,567.89
console.log(eur); // 1.234.567,89 €
console.log(jpy); // ￥1,234,568

✅ Perfect for:

- Financial apps
- Displaying dates and currencies
- Internationalization

Don’t reinvent the wheel. Use what JavaScript already has out of the box.