Lexical Structure

Javascript is an interpreted programming language used for creating dynamic web pages. It is embedded in the most popular web browsers where client side scripts can interact with users, and dynamically update content in the browser window. It is a simple to use programming language, but that doesn't mean that you should dive right in and start writing programs. First things should come first and the first thing to know about Javascript to know is how to write programs with it.

The lexical structure of a programming language is its most fundamental rules. These rules tell you how to comment your program, and what character to use to separate simple statements from each other, and more. The lexical structure of a programming language is its most basic syntax. In this article I am going to outline the lexical structure of Javascript.

Lexical Structure includes:

• Case Sensitivity: Case sensitivity means that meaning of a thing can change with different capitalization. Javascript is a case sensitive language. This means that names and keywords in your programs must be capitalized consistently.
• Semicolons: Semicolons are used to separate simple statements from each other. In Javascript, semicolons are optional. It is a good programming practice to include semicolons for the sake of clarity.
• Whitespace: Javascript ignores whitespace. Whitespace includes spaces, tabs, and newlines. You can take advantage of this rule by indenting your code in order to make it more readable.
• Comments: Comments are used to tell what a line or section of code does. They are ignored by the Javascript.
• Literals: A literal is a value that is represented directly in code. Some examples of literals are numbers, quoted strings, boolean values, and null. Literals represent fixed values.
• Identifiers: An identifier is a name. Identifiers are used to name variables and functions.
• Keywords: A keyword is a word that has special meaning to the language. It is part of the language itself. Any keyword is not a valid identifier.

"The lexical structure of a programming language is its most fundamental rules."

Now that we have covered the lexical structure of Javascript we can use what we know to write our first program:

// A comment

/* Another comment */

<!-- Another comment

// An empty statement terminated with a semicolon

;

// A numeric literal, a string literal, and a boolean literal

0;

'Hello world! This is a string literal';

true;

// An identifier

var myVariable;

// A keyword

false;