Function Basics
James Gibson
Objectives
-
Describe why a function is useful
-
Label the syntax of a function
-
Declare and invoke a function
-
Use the keyword return
What is a function?
A reusable sequence of instructions that achieve a specific task
Example usage of a function:
- Calculating change (payment - total = change)
- Converting text (SHOUTING)
- Given a word, calculate it's scrabble score
- Given a year, determine if it is a leap year
Why do we use functions?
Reproducable
const hello = (name) => {
console.log(`Hello, ${name}`);
};
hello('James')
"Hello, James"Recap
Talk to your neighbor
In your own words, describe the purpose of a function
Give an example of a task to use a function for
Questions?
Syntax of a function
const hello = () => {
console.log('Hello World');
};Arrow Syntax
Your instructions go here.
Parens
Function name
^
ES6
Syntax of a function
function multiply(a, b) {
return a * b;
};Parameters
return keyword
^
ES5
function keyword
Name
Syntax of a function
multiply(3, 4)
// 12Arguments
Invoking a function
Function name
How the returned or logged information is shown in documentation
Recap Function Syntax
const multiply = (a, b) => {
return a * b;
};Identify and label each part of the function
Name
Parameters
Arrow Syntax
return keyword
Create and Invoke
Let's go code some stuff!
return keyword
const sum = (a, b) => {
return a + b;
};
sum(5,3) // 8const multiply = (a, b) => {
return a * b;
};
multiply(2, 3) // 6return keyword
const arrayLength = (array) => {
return array.length;
};
arrayLength([1,2,3]) // 3
Define and invoke a function named "arrayLength" that accepts an array as its argument and returns the length of that array.
Recap
const division = (a, b) => {
return a / b;
};
division(6, 3) // 2What is a function?
What part of a function is this?
Describe this line
Why do we use "return"?