labyrinth.js

var guards = [];
guards.push(!true); //guard 0, always lies
guards.push(true);  //guard 1, always true

var doors = [];
doors.push("certain doom"); //door 0, certain doom
doors.push("the castle");   //door 1, the castle 

//Does door 0 lead to the castle?
var theTruth = (doors[0] == "the castle"); //false

//What would the guards say if asked directly?
var guard0Answer = (guards[0] == theTruth); //true (a lie!)
var guard1Answer = (guards[1] == theTruth); //false

//What would the guards say the other guard would say?
var guard0SaysGuard1WouldSay = (guards[0] == guard1Answer); //true (a lie!)
var guard1SaysGuard0WouldSay = (guards[1] == guard0Answer); //true (he lies!)

console.log("Does Door 0 lead to the castle? " + theTruth);
console.log("Guard 0, does Door 0 lead to the castle? " + guard0Answer);
console.log("Guard 1, does Door 0 lead to the castle? " + guard1Answer);

console.log("Guard 0, Would Guard 1 say that Door 0 leads to the castle? " + guard0SaysGuard1WouldSay);
console.log("Guard 1, Would Guard 0 say that Door 0 leads to the castle? " + guard1SaysGuard0WouldSay);