JS to realize the number to amount price thousand separator

Go straight to the code ：

function format_with_mod(number) {
  let n = number;
  let r = '';
  let temp = '';
  do {
    //  Modulus value ,  Used to get the top three digits , There may be decimals here 
    mod = n % 1000;
    //  Is the value greater than 1, It's a condition to continue 
    n = n / 1000;
    //  High three position 
    temp = ~~mod;
    // 1. fill : n > 1  The cycle is not over ,  Just fill it with, for example  1 => 001
    //  Otherwise temp = ~~mod When , 1 001,  Will become  "11"
    // 2. Splicing “,”
    r = (n >= 1 ? `${temp}`.padStart(3, '0') : temp) + (!!r ? ',' + r : '');
  } while (n >= 1);
  const strNumber = number + '';
  let index = strNumber.indexOf('.');
  //  Splice decimal parts 
  if (index >= 0) {
    r += strNumber.substring(index);
  }
  return r;
}