Arrow functions

Arrow functions

• A shorter way to write a function: const square = (n) => n * n;.
• With a single expression after =>, the value is returned automatically — no return, no { }.

const square = (n) => n * n;
console.log(square(5));   // → 25

More than one parameter

• List the parameters in the brackets, separated by commas.

const add = (a, b) => a + b;
console.log(add(3, 4));   // → 7

Watch out

• Need a longer body? Use { } and then you must write return yourself.
• Arrow functions shine as short helpers — you will hand them to .map and .filter when we reach array methods.

Common mistakes

• x => x + 1 is a short function; with no braces it returns the expression.
• Arrow functions are handy as arguments to array methods.

Now you try

• Write each arrow function.
• Press Check answer to test it.