Functions

Functions

• A function is a named block of code you can run again and again.
• function name(params) { ... return value; }. The params are the inputs.
• return hands a value back to whoever called the function.

function square(n) {
  return n * n;
}
console.log(square(6));   // → 36

Functions that just do something

• A function can do something (like print) instead of returning a value.
• Call it by writing its name and brackets: greet("Ada").

function greet(name) {
  console.log("Hi, " + name);   // → Hi, Ada
}
greet("Ada");

Watch out

• The names in the brackets (n, name) are parameters — they only exist inside the function.
• A function with no return gives back undefined. Add return when you want an answer out.

Common mistakes

• return gives back a value; without it a function returns undefined.
• Call the function with ().

Now you try

• Write each function — it is called for you in the check.
• Press Check answer to test it.