A simple example using Maybe monad of MonetJS

monetjs_example#1

// Run the code with NodeJS

var Monet = require('monet');

function getValue (obj, keysString) {
	var keys = keysString.split('.');

	var curr = obj;

	keys.forEach(function (key) {
		if (curr) {
			curr = curr[key];
		}
	});

	return Monet.Maybe.fromNull(curr);
}

function print (value) {
	console.log(value);

	return value;
}

var add = function (a, b) {
	return a + b;
}.curry();

var test = {
	yo: {
		first: 2,
		value: {
			second: 4
		}
	}
};

// Play with the second parameter of getValue and see what happens when you try non-existing keys
var first = getValue(test, 'yo.first');
var second = getValue(test, 'yo.value.second');

var result = first.ap(second.map(add));

if (result.isSome()) {
	result.map(print);
} else {
	console.log('None');
}