JavaScript Syntax

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

JavaScript Programs

A computer program is a list of "instructions" to be "executed" by the computer.

In a programming language, these program instructions are called statements.

JavaScript is a programming language.

JavaScript statements are separated by semicolons.

var x = 5;
var y = 6;
var z = x + y;

JavaScript Statements

JavaScript statements are composed of:

Values, Operators, Expressions, Keywords, and Comments.

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 keywords are used to identify actions to be performed.

The var keyword tells the browser to create a new variable:

var x = 5 + 6;
var y = x * 10;

Not all JavaScript statements are "executed".

Code after double slashes // or between /* and */ is treated as a comment.

Comments are ignored, and will not be executed:

var x = 5;   // I will be executed
// var x = 6;   I will NOT be executed