JavaScript Syntax

JavaScript syntax is the set of rules, how JavaScript programs are constructed:

var x, y, z;       // How to declare variables

x = 5; y = 6;      // How to assign values

z = x + y;         // How to compute values

JavaScript Values

The JavaScript syntax defines two types of values: Fixed values and variable values.

Fixed values are called literals. Variable values are called variables.

JavaScript Literals

The most important rules for writing fixed values are:

Numbers are written with or without decimals:

10.50

1001

Strings are text, written within double or single quotes:

"John Doe"

'John Doe'

JavaScript Variables

In a programming language, variables are used to store data values.

JavaScript uses the var keyword to declare variables.

An equal sign is used to assign values to variables.

In this example, x is defined as a variable. Then, x is assigned (given) the value 6:

var x;

x = 6;

JavaScript Operators

JavaScript uses arithmetic operators ( + - * / ) to compute values:

(5 + 6) * 10