What is a variable?

A variable is a named box that remembers a value. You put something in it, read it back later, and change it whenever you need to. Almost every game is really just a pile of variables changing over time — a score, a position, a timer.

1. Make one with let

Write let, a name, =, and a starting value. Here score starts at 0, and we show it on screen:

let score = 0;

function draw() {
  cls(1);
  print('Score: ' + score, 8, 8, 7);
}

The name score now stands for that value everywhere you use it.

2. Change it any time

That is the whole point of a variable — it can vary. Give it a new value with =, or build on the one it already has. Here the score climbs by 1 each time you press space:

let score = 0;

function update() {
  if (keyp(' ')) {
    score = score + 1;   // take the old score, add 1, store it back
  }
}

function draw() {
  cls(1);
  print('Score: ' + score, 8, 8, 7);
}

3. Values come in types

So far score held a number. But a variable can hold other kinds of value too, called types. The main ones you will meet:

• Number — 0, 7, 3.5. Scores, positions, timers.
• String — text like Spark, written in quotes. Names, messages.
• Boolean — true or false. Yes/no facts, like "is the game over?"
• Object — a bundle of related values grouped together.
• Array — a list of many values.

Each type gets its own lesson next — this one is just the big idea: a name that holds a value you can change.

What you learned

• A variable is a named box that remembers a value.
• let name = value makes one; name = newValue changes it.
• score = score + 1 stores a new value built from the old one.
• Values have types — number, string, boolean, object, array — each covered next.