//js方法格式化數字，加入千分符，並可以指定小數點位數
function number(s, n) {
  n = n >= 0 && n <= 20 ? n : 2;
  s = parseFloat((s + "").replace(/[^\d\.-]/g, "")).toFixed(n) + "";
  var l = s
    .split(".")[0]
    .split("")
    .reverse(),
    r = s.split(".")[1];
  r = r == null ? "" : "." + r;
  var t = "";
  console.log
 
(l)
  if (l[l.length - 1] === '-') {//負數不需要分隔號,

    for (var i = 0; i < l.length; i++) {
      if (l[i]==='-') {
        t += l[i]+""
        continue
      }
      //不是陣列的倒數第二個元素才加"," ["0", "4", "5", "-"]
      t += l[i] + ((i + 1) % 3 == 0 && i + 1 != l.length-1 ? "," : "");

      //i + 1 != l.length
 
會變成-,540.00,因為在5時元素位置2+1為3非陣列長度
      //t += l[i] + ((i + 1) % 3 == 0 && i + 1 != l.length ? "," : "");
    }
  }
  else {
    for (var i = 0; i < l.length; i++) {
      t += l[i] + ((i + 1) % 3 == 0 && i + 1 != l.length ? "," : "");
    }
  }
  return (
    t
      .split("")
      .reverse
 
()
      .join("") + r
  );
}