Add a thousands separator to a total with Javascript or jQuery?

Question

I have a function that sums a column of data in an html table. It does so admirably only I would like to have it put the commas in there that are needed to separate the thou

Answer 1

a recursive solution:

function thousands(amount) {
  if( /\d{3}\d+/.test(amount) ) {
    return thousands(amount.replace(/(\d{3}?)(,|$)/, ',$&'));
  }
  return amount;
}

another split solution:

function thousands (amount) {
  return amount
    // reverse string
    .split('')
    .reverse()
    .join('')
    // grouping starting by units
    .replace(/\d{3}/g, '$&,')
    // reverse string again
    .split('')
    .reverse()
    .join('');
}