JavaScript - Variables

Variables = Data Containers
JavaScript variables are containers for data.

JavaScript variables can be declared in 3 ways:

Modern JavaScript

• Using let
• Using const

Older JavaScript

• Using var

Examples of Using let:
let x = 5;
let y = 6;
let z = x + y;

Examples of Using Const
const x = 5;
const y = 6;
const z = x + y;

Variables are labels for data values. Variables are containers for storing data.

JavaScript Identifiers

• Variables are identified with names called identifiers.
• Names can be short like x, y, z.
• Names can be descriptive like age, sum, carName.

The rules for constructing names (identifiers) are:

• Names can contain letters, digits, underscores, and dollar signs.
• Names must begin with a letter, a $ sign or an underscore (_).
• Names are case sensitive (X is different from x).
• Reserved words (JavaScript keywords) cannot be used as names.