javascript · level 1 · unit 4 · lesson 2
- meet it
- guess first
- your turn
- fix it
- nailed it
Tap a green word if you get lost.
meet it
is the other path at the fork.
An if on its own either runs its block or skips it. Often you want a plan B. else means otherwise: when the condition is false, JavaScript runs the block after else instead.
At a fork you always take exactly one path. With if and else, exactly one block runs. Never both, and never neither.
else goes straight after the closing } of the if. It has no condition of its own, so it needs no round brackets. Its lines get their own curly brackets.
let biscuits = 0;
if (biscuits === 0) {
console.log("Time to go to the shop.");
} else {
console.log("Have a biscuit!");
} Read else as “otherwise”.
guess first
Full marks or not? Make a guess.
Guess before you run it. Wrong guesses are how you learn, and nothing is marked.
let score = "10";
if (score === 10) {
console.log("Full marks!");
} else {
console.log("Not quite.");
}
your turn
Your turn. Meet a pet that is not a dog.
Type any pet except a dog between the quotes, then press run to see plan B.
fix it
The cinema code will not run. Fix it!
- JavaScript cannot read line 4. Look at what comes straight after
else. elsehas no condition of its own. It catches everything theifdid not.- Delete (ticket === "no") so line 4 reads } else {, then press run.
nailed it
your program has a plan b now. :D
elseruns when theifcondition isfalse.- Only one path runs: the
ifblock or theelseblock. elsehas no condition and no round brackets.
new words in your collection
- else
This lesson isn’t saved. A free account remembers every lesson you finish.