maybe in js

maybe.js

var Maybe = function(x) {
  this.__value = x;
};

Maybe.of = function(x) {
  return new Maybe(x);
};

Maybe.prototype.isNothing = function() {
  return (this.__value === null || this.__value === undefined);
};

Maybe.prototype.map = function(f) {
  return this.isNothing() ? Maybe.of(null) : Maybe.of(f(this.__value));
};



Maybe.of('Malkovich Malkovich').map(match(/a/ig));
//=> Maybe(['a', 'a'])

Maybe.of(null).map(match(/a/ig));
//=> Maybe(null)

Maybe.of({
  name: 'Boris',
}).map(_.prop('age')).map(add(10));
//=> Maybe(null)

Maybe.of({
  name: 'Dinah',
  age: 14,
}).map(_.prop('age')).map(add(10));
//=> Maybe(24)