JavaScript Format numbers as money


Example

Fast and short way to format value of type Number as money, e.g. 1234567.89 => "1,234,567.89":

var num = 1234567.89,
    formatted;

formatted = num.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,');  // "1,234,567.89"

More advanced variant with support of any number of decimals [0 .. n], variable size of number groups [0 .. x] and different delimiter types:

/**
 * Number.prototype.format(n, x, s, c)
 * 
 * @param integer n: length of decimal
 * @param integer x: length of whole part
 * @param mixed   s: sections delimiter
 * @param mixed   c: decimal delimiter
 */
Number.prototype.format = function(n, x, s, c) {
    var re = '\\d(?=(\\d{' + (x || 3) + '})+' + (n > 0 ? '\\D' : '$') + ')',
        num = this.toFixed(Math.max(0, ~~n));

    return (c ? num.replace('.', c) : num).replace(new RegExp(re, 'g'), '$&' + (s || ','));
};

12345678.9.format(2, 3, '.', ',');  // "12.345.678,90"
123456.789.format(4, 4, ' ', ':');  // "12 3456:7890"
12345678.9.format(0, 3, '-');       // "12-345-679"
123456789..format(2);               // "123,456,789.00"