JavaScript: Thousands separator function

To add a comma thousands separator every 3 digits in a number using JavaScript, use the following function:

function addThousandsSeparator(value) {
    return value.toString().replace(/(\d)(?=(\d\d\d)+(?!\d))/g, "$1,");
}

Example output

var list = [
    1,
    1.03,
    10,
    100,
    1000,
    1000.03,
    9000,
    10000,
    100000,
    1000000,
    10000000,
    100000000,
];

for (var i in list) {
    var num = list[i];
    console.log(num, "=>", addThousandsSeparator(num));
}

// Example output
        1 => '1'
     1.03 => '1.03'
       10 => '10'
      100 => '100'
     1000 => '1,000'
  1000.03 => '1,000.03'
     9000 => '9,000'
    10000 => '10,000'
   100000 => '100,000'
  1000000 => '1,000,000'
 10000000 => '10,000,000'
100000000 => '100,000,000'