implementation of and increment for any number's roundding. the Math.round(x) is equivalent to genericRound(x, 1)

generic-round.tsx

/**
 * 实现任意 increment 的任意数字的 rounding 操作;
 * 比如 Math.round(n) 其实就是 genericRound(n, 1) 的特化
 */
export function genericRound(n: number, inc: number): number {
  if (inc === 0) return n;
  const d = (n % inc);
  if (d >= (inc / 2)) return n + (inc - d);
  return n - d;
}


genericRound(23.4, 0.5) // 23.5
genericRound(23.8, 0.5) // 24

genericRound(23.11, 0.1) // 23.1
genericRound(23.18, 0.1) // 23.2