Functions Revisited

We can write our own functions!

Creating Functions

How do we write our own functions? →

start with the keyword, function
followed by the name of your function
followed by parentheses
followed by an optional list of comma separated parameters (input)
close parentheses
a block of code between curly braces

An Example

function foo() {
	console.log("FOO!");
}

A Function With Parameters (Input)

How do we create a function that has parameters or inputs? →

function foo(s) {
	console.log(s + "!");
}

Giving Back Values (Output)

How do we create a function that gives back values? →

// use the keyword, return
function foo(s) {
	return s + "!";
}
console.log(foo("hi"));

A Few Notes About Functions

can be defined anywhere (that is, you can use them even if they are defined later in your file)
inputs and outputs are optional
a functions is another type!
let’s define a function… and prove this (how do we show type?)

A Function is Another Type!

Demos

factorial function
sum of three numbers function