XOR

The Boolean operators have an order: First NOT, then AND, last OR. If you want to change this order, use parentheses:

let x1 = true || false && false;
let x2 = (true || false) && false;
let x3 = !false && false;
let x4 = !(false && false);

In the 1st line && is evaluated first. x1 is true. In the 2nd line || is evaluated first. x2 is false. In the 3rd line ! is evaluated first. x3 is false. In the 4th line && is evaluated first. x4 is true.

In the following task you should code another important gate, the XOR (eXclusive OR) gate.

Write a function xor that takes two Boolean values. If both values are different, the result should be true. If both values are the same, the result should be false.

I.e.: The calls xor(true, false) and xor(false, true) should return true. The calls xor(true, true) and xor(false, false) should return false.

+ Hint

Write an expression that returns true only if the first parameter is true and the second is false. Then write an expression that returns true only if the first parameter is false and the second is true. Combine both expressions appropriately.

+ Solution

function xor(a, b) {
  return a && !b || !a && b;
}