Nothing to do when it is false

Challenge 16 of 16

Two badges and one thing missing. The left question is true so its badge is green; the right one is false, and an if on its own has no way of saying what to do about that.

Set both marks so the target is matched, and meet else next.

Your code JavaScript

Set both marks so the target is matched, and meet else next.

Console print() output

0 / 30 frames · 400×400

Target

Yours

Yours over Target — ghosted shapes are in the target but missing from yours

Results

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Penalties: none this run

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Lesson If

Last topic a question had an answer and that was the end of it. This topic gives the answer something to do.

if (score > 100) {
shapeColour(GREEN);
}

Read it as a sentence: if score is bigger than 100, pick up a green pen. The question goes in the round brackets. The lines that wait on it go in the curly brackets.

When the answer is true, the lines in the curly brackets run, and then the sketch carries on underneath as usual.

When the answer is false, those lines are skipped. Not undone, not delayed — skipped, as though they were not there. This is the first time your lines have not simply run one after the other from the top.

That is why a grey badge is worth looking at twice. It is not grey because something said so. It is grey because the pen was already grey and nothing ran to change it.

Anything can go inside the curly brackets. One line, three lines, a whole shape, a background, a number put into a box:

if (temperature > 25) {
backgroundColour(ORANGE);
shapeColour(RED);
}

A box changed inside an if keeps its new number afterwards, so an answer up here can reach a line much further down.

Watch what comes after the brackets, though. If you pick up another colour below the if, that one wins — the last pen named before a shape is the one it is drawn with. That is the same top-to-bottom rule you have always had.

The line at the bottom of every challenge in this course shows you the numbers the question is asking about, so you can always see what it is working from.

One thing an if cannot do yet: say what to do when the answer is false. That is the next topic, and it is called else.