developer-roadmap/src/lib/number.ts

export const formatter = Intl.NumberFormat('en-US', {
  useGrouping: true,
});

export function formatCommaNumber(number: number): string {
  return formatter.format(number);
}

export function decimalIfNeeded(number: number): string {
  return number % 1 === 0 ? number.toString() : number.toFixed(1);
}

export function humanizeNumber(number: number): string {
  if (number < 1000) {
    return formatCommaNumber(number);
  }

  if (number < 1000000) {
    return `${decimalIfNeeded(number / 1000)}k`;
  }

  return `${decimalIfNeeded(number / 1000000)}m`;
}