A framework to build a number manipulation library with built in functions for currency, padding and grouping

lumber.js

// A framework to build a number manipulation library
// Usage: lumber(5).padLeft(2).value;
// -> 05
// Usage: lumber(5).padRight(2).value;
// -> 50
// Usage: lumber(5.1).currency().value;
// Default arguments for '.currency()' is a template of value: '($0.00)'
// -> $5.10
// Usage: lumber(-5.1).currency().value;
// -> ($5.10)
// Usage: lumber(4349847.18534).group().value;
// -> 4,349,847.18534
// Usage: lumber(4349847.18534).round(2).group().value;
// -> 4,349,847.19
// Usage: lumber(53234.1).currency('€0.00').value;
// -> €53234.10
// Usage: lumber(53234.1).currency('€0.00').group().value;
// -> €53,234.10
function lumber(number) {
  var wrapper = {
    number : number,
    value  : number.toString()
  };
  if (!/^[0-9\.\-]+$/.test(number.toString())) {
    throw 'padNumber: Invalid type';
  }
  for (var fn in lumber) {
    wrapper[fn] = function (fn) {
      return function () {
        return lumber[fn].apply(null, [wrapper].concat([].slice.call(arguments)));
      };
    }(fn);
  }
  return wrapper;
}

lumber.clone = function (wrapper) {
  var clone = {};
  for (var k in wrapper) {
    clone[k] = wrapper[k];
  }
  return clone;
};

lumber.padLeft = function (wrapper, n) {
  var padding = new Array(n + 1).join('0');
  var start = padding.substr(0, n - wrapper.value.length);
  wrapper.value = start + wrapper.value;
  return wrapper;
};

lumber.padRight = function (wrapper, n) {
  var padding = new Array(n + 1).join('0');
  var start = padding.substr(0, n - wrapper.value.length);
  wrapper.value = wrapper.value + start;
  return wrapper;
};

lumber.group = function (wrapper, char) {
  if (typeof char === 'undefined') {
    char = ',';
  }
  wrapper.value = wrapper.value.replace(/[0-9]+/, function (b) {
    b = b.split('').reverse();
    for (var i = b.length; i >= 0; i--) {
      if (i > 0 && i % 3 === 0) {
        b.splice(i, 0, char);
      }
    }
    return b.reverse().join('');
  });
  return wrapper;
};

lumber.currency = function (wrapper, temp) {
  if (typeof temp === 'undefined') {
    temp = '($0.00)';
  }
  function currency() {
    var a = wrapper.number.toString().match(/[0-9]+/g).slice(0, 2);
    var n = temp.match(/[0]+/g).slice(-1)[0].length;
    var isNegative = wrapper.number < 0;
    var i = false;
    if (a.length === 1) {
      a[1] = new Array(n + 1).join('0');
    } else {
      a[1] = lumber(Number(a[1])).padRight(n).value;
    }
    wrapper.value = temp.replace(/\)|\(|-|[0]+/g, function (b) {
      var isZero = /0/.test(b);
      if (isZero && !i) {
        i = true;
        return a[0];
      } else if (isZero) {
        return a[1];
      } else if (isNegative && !isZero) {
        return b;
      }
      return '';
    });
    return wrapper;
  }
  return currency();
};

lumber.round = function (wrapper, n) {
  var number = Number(wrapper.value);
  wrapper.value = (Math.round(number * Math.pow(10, n)) / Math.pow(10, n)).toString();
  return wrapper;
};