Pass or fail — visuco

Challenge 4 of 16

This is what an else is really for: a question with two named outcomes and nothing left over. The bar shows the mark and the badge shows the verdict, so both halves of the picture come from the one number.

Set the pass mark so the target is matched.

Your code JavaScript

Set the pass mark so the target is matched.

Console print() output

0 / 30 frames · 400×400

Target

Yours

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

Results

Press Run to check your code

Penalties: none this run

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Lesson Or Else

An if on its own can only say what to do when the answer is true. When it is false, nothing happens — and a badge that stayed grey because nothing happened is a strange thing to have to explain.

else is the other half.

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

Read it as one sentence: if score is over 100 use green, or else use red. The else has no question of its own. It does not need one, because it means everything the if did not catch.

Exactly one of those two blocks runs. Never both, never neither. That is worth saying plainly, because it is what makes an else so restful to read: whatever happens, you know something happened.

Notice what you no longer need. In the last topic every badge had a grey pen picked up first, in case the if did not run. With an else naming a colour on each side there is nothing for a fallback to cover, so it can go.

Either side can hold as many lines as it likes, and they need not do the same kind of thing:

if (score > 200) {
howBig = 260;
} else {
howBig = 100;
}

A colour, a size, a place, a whole background, even a different shape altogether. The one rule is that the else comes straight after the if's closing curly bracket, on the same line as it in these challenges.

Two questions written one after another are two separate decisions. Ask the same thing twice with the colours swapped over and you get two lamps, exactly one of which is lit.

So far every question has been the same one: is this bigger than that. The next topic has the rest of them.