ES5 Bitmask

bitmask.js

function Bitmask(value) {
  function parse(value){
    return Number(parseInt(value)||0);
  }
  return Object.create({}, {
    _value: {
      value: parse(value),
      enumerable: false,
      configurable: false,
      writable: true
    },
    set: {
      value: function (value) {
        this._value = parse(value);
        return this._value == value;
      },
      enumerable: false,
      configurable: false,
      writable: false
    },
    has: {
      value: function (bit) {
        return (this._value & parse(bit)) == bit;
      },
      enumerable: false,
      configurable: false,
      writable: false
    },
    add: {
      value: function (bit) {
        this._value = this._value | parse(bit);
        return this._value;
      },
      enumerable: false,
      configurable: false,
      writable: false
    },
    remove: {
      value: function (bit) {
        this._value = this._value & ~parse(bit);
        return this._value;
      },
      enumerable: false,
      configurable: false,
      writable: false
    },
    toString: {
      value: function (base) {
        return this._value.toString(parse(base) || 10);
      },
      enumerable: false,
      configurable: false,
      writable: false
    }
  });
}