Currency Formatting Fundamentals

Currency formatting is a critical component of internationalization and localization. It ensures that monetary values are displayed correctly according to the local customs, which can vary significantly across different regions.

• **Locale**: A set of parameters that define the user's language, region, and any special variant preferences.
• **Currency Code**: A three-letter code defined by the ISO 4217 standard that represents a specific currency.
• **Decimal Separator**: The symbol used to separate the integer part from the fractional part of a number.
• **Thousands Separator**: A symbol used to separate groups of thousands in large numbers.

Follow these steps to format currency correctly:

1. Identify the user's locale.
2. Get the currency code for the user's region.
3. Determine the appropriate decimal and thousands separators.
4. Format the currency value using the identified parameters.

const numberFormat = new Intl.NumberFormat("en-US", {
    style: "currency",
    currency: "USD",
});

console.log(numberFormat.format(1234567.89)); // Output: $1,234,567.89

• Always use the appropriate locale for formatting.
• Utilize built-in formatting libraries (e.g., Intl.NumberFormat in JavaScript).
• Test with different locales to ensure correct formatting.
• Be aware of the currency symbol positioning (before or after the number).