题解 | #分隔符#

搞得复杂

function _comma(number) {
  let char = /\d/.test((number + "")[0]) ? "" : (number + "")[0];
  let arr = (number + "").replace(/\D/, "").split("").reverse();
  let j = 0;
  for (let i = 0; i < arr.length; i++) {
    if (i % 3 === 0 && i > 0) {
      arr.splice(i + j, 0, ",");
      j++;
    }
  }
  return char + arr.reverse().join("");
  }