Similar to algebra
Helps you represent data or values
Used to help your program “remember” values
Can be thought of as a “box” that we put values in
In programming, you store values in variables if you plan on referencing that value at a later time
Variables are created by declaring them
Use the var keyword to declare a variable
If you declare a variable without assigning it an initial value, the value of that variable will be undefined
// declaring a variable
var firstName;
Variables only need to be declared once
We can provide variables with a value by assigning a value to the variable
An = (equal sign) is used to assign a value to variable
// declaring a variable
var firstName;
// assigning a value to the variable
firstName = "Cletus";
We can both declare and assign variables in one step
This would be done if the developer wanted to set the initial value of the variable
// declare and assign an intial value to a variable
var score = 0;
= (equal sign) to change or reassign a value of a variable
// declare and assign a value of 0 to the score variable
var score = 0;
// changing the value of the score variable from 0 to 3
score = 3;
| Do | Don’t |
|---|---|
| Use variable names that start with a letter, $, or _ | Use variable names that start with a number |
| Use variable names that includes letters, numbers, $ or _ | Create variable names that include a “-”, “.” or space |
| Use snake case when creating variable names made up of more than one word, for example: firstName | Create variable names that use Javascript keywords such as var, function or switch |
Variables names should describe the kind of information the variable stores
Here’s a list of Javascript’s reserved keywords