This document discusses variables and functions in JavaScript. Variables can represent different data types and be used to store and represent data. Functions contain statements and instructions to perform tasks and can be called using events like onclick to trigger the function. Examples are provided of using variables to store and display random numbers generated by JavaScript, which could aid in creating a rock-paper-scissors game by having the computer randomly select rock, paper, or scissors for each round.

1. S
Chapter 3 - Web Topics
JavaScript
CSC 103

2. Variables
keyword var
§ Can represent a string, number or another
variable or a combination of values and
hold data.

3. Variables
string
number
concatenation
variable variablestring
Operator (joins)
Variable name

4. Functions
concatenation
keyword function
§ Contains one or more statements or
instructions to carry out.
Defines a function

5. Functions
Defining a Function
concatenation
Function name
Changes opacity of element
with id name “pic”
Displays text on a web
page in an element
with Id name of ”message”
Curly braces
Id name of HTML element

6. Calling the Function
concatenation
onclick event
§ Functions can be called and run
with an onlick event on a button.
Button will run the hidePatrick() function

7. Ex 9a Variable Example

8. Ex 9a Variable Example
HTML
Empty until
function is run

9. Ex 9a Variable Example
CSS
Adjusts
font size
of 2
HTML
elements

10. Ex 9a Variable Example
JavaScript
Variables declared
and assigned
Function definition
Joins variables with a space (string)

11. Ex 10a Random Number
HTML & CSS

12. Ex 10a Random Number
JavaScript
Method that generates
a random number 0-1
Multiplied by 10
Rounded up to nearest
integer 1-10
Variable displayed in id
area on page

13. Ex 10a Random Number
JavaScript

14. Ex 10a Random Number
JavaScript
Thinking ahead (critically)…
§ How can using a random number aid in
creating a rock-paper-scissors game?
Paper ScissorsRockYou choose a button…
At the same time:
Computer generates a
random 1, 2 or 3