number_format.js

function number_format(_number, _cfg){
            function obj_merge(obj_first, obj_second){
                var obj_return = {};
                for (key in obj_first){
                    if (typeof obj_second[key] !== 'undefined') obj_return[key] = obj_second[key];
                    else obj_return[key] = obj_first[key];
                }
                return obj_return;
            }
            function thousands_sep(_num, _sep){
                if (_num.length <= 3) return _num;
                var _count = _num.length;
                var _num_parser = '';
                var _count_digits = 0;
                for (var _p = (_count - 1); _p >= 0; _p--){
                    var _num_digit = _num.substr(_p, 1);
                    if (_count_digits % 3 == 0 && _count_digits != 0 && !isNaN(parseFloat(_num_digit))) _num_parser = _sep + _num_parser;
                    _num_parser = _num_digit + _num_parser;
                    _count_digits++;
                }
                return _num_parser;
            }
            if (typeof _number !== 'number'){
                _number = parseFloat(_number);
                if (isNaN(_number)) return false;
            }
            var _cfg_default = {
                before: '',
                after: '',
                decimals: 2,
                dec_point: '.',
                thousands_sep: ','
            };
            if (_cfg && typeof _cfg === 'object'){
                _cfg = obj_merge(_cfg_default, _cfg);
            }
            else _cfg = _cfg_default;
            _number = _number.toFixed(_cfg.decimals);
            if(_number.indexOf('.') != -1){
                var _number_arr = _number.split('.');
                var _number = thousands_sep(_number_arr[0], _cfg.thousands_sep) + _cfg.dec_point + _number_arr[1];
            }
            else var _number = thousands_sep(_number, _cfg.thousands_sep);
            return _cfg.before + _number + _cfg.after;
        }