Booleans

A boolean is the simplest type: it is either true or false. Games are full of yes/no facts — is the game over? is the player jumping? did we hit something? — and a boolean holds the answer.

1. true and false

let gameOver = false;
let hasKey = true;

function draw() {
  cls(1);
  print('Game over? ' + gameOver, 8, 8, 7);
  print('Has key? ' + hasKey, 8, 20, 7);
}

2. Comparisons make booleans

Most booleans come from comparing values. Each of these gives back true or false:

• a > b, a < b, a >= b, a <= b — bigger / smaller.
• a === b — equal (three equals). a !== b — not equal.

let health = 0;

function draw() {
  cls(1);
  print('health > 0 : ' + (health > 0), 8, 8, 8);
  print('health === 0 : ' + (health === 0), 8, 20, 7);
}

3. Combine and flip

Join conditions with && ("and") and || ("or"), and flip one with ! ("not"):

• a && b — true only if both are true.
• a || b — true if either is true.
• !a — the opposite of a.

let health = 5;
let hasShield = true;

function draw() {
  cls(1);
  let safe = health > 0 && hasShield;
  print('safe? ' + safe, 8, 8, 11);
  print('in danger? ' + !safe, 8, 20, 8);
}

Booleans are what if statements ask about — you will use them everywhere once you reach If statements next.

What you learned

• A boolean is true or false — a yes/no fact.
• Comparisons (>, <, ===, !==) produce booleans.
• Use === to compare, not =.
• Combine with && (and), || (or), and flip with ! (not).