Functions - A First Look

Objectives

1. Be able to articulate what a function is and how they are used
2. Describe in your own words why you write functions
3. Write and use a simple function that takes arguments and returns a value

Terms

• function

• parameter

• argument

• return value

• invoke

What are functions?

A set of statements that perform a task or calculate a value

1

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Functions

1

Declaring a Function

function getHello() {
    // return the word Hello
    return "Hello";
}

getHello();
//Hello

function keyword

name

body

Declaring a Function

function formatMessage(recipient,msg) {
    // print the message to the console
    return recipient + ' You have a message:\n ' + msg;
}

formatMessage("John", "Your appointment is at 6pm");

//John You have a message:
// Your appointment is at 6pm

function keyword

name

body

parameters

Example

Write a function that returns the sum of two numbers

Exercise 1

Write a function that multiplies two numbers

Exercise 2

Write a function that adds two numbers then multiplies that result by a third number