Javascript Introduction

JavaScript Tutorial

Javascript
what the heck is it? Is it a really difficult programming language that casual web designers should be afraid of? What is it used for? Hopefully we'll be able to answer these questions for you and more in this tutorial

JavaScript
has been around for several years. The main benefit of Javascript is to add additional interaction between the website and its visitors with just a little extra work by the web developer. Javascript allows industrious web masters to get more out of their website than HTML and CSS can provide.

By definition, JavaScript is a client-side scripting language. This means the web surfer's browser will be running the script. The opposite of client-side is server-side, which occurs in a language like PHP. PHP scripts are run by the web hosting server.

There are many uses (and abuses!) for the powerful JavaScript language. Here are a few things that you may or may not have seen in your web surfing days:

Clocks
Mouse Trailers (an animation that follows your mouse when you surf a site)
Drop Down Menus shows
Alert Messages display
Popup Windows open
HTML Form Data Validation

Tutorial Overview

Before you begin this tutorial, you should have basic knowledge of HTML. Check out our Beginner and HTML tutorials to brush up on the basics.

This tutorial will cover the basics of JavaScript, from where to place your JavaScript all the way to making your own JavaScript functions. Also, there will be some good programming practice tips throughout this tutorial.

We recommend that you read a few lessons a day and practice what you have learned. This will help you to absorb the material more readily than if you blasted through the entire tutorial in one sitting!

What You Should Already Know

Before you continue you should have a basic understanding of the following:

HTML / XHTML

What is JavaScript

JavaScript was designed to add interactivity to HTML pages
JavaScript is a scripting language
A scripting language is a lightweight programming language
JavaScript is usually embedded directly into HTML pages
JavaScript is an interpreted language (means that scripts execute without preliminary compilation)
Everyone can use JavaScript without purchasing a license

Java and JavaScript are the same

Java and JavaScript are two completely different languages in both concept and design!

Java (developed by Sun Microsystems) is a powerful and much more complex programming language - in the same category as C and C++.

What can a JavaScript do

JavaScript gives HTML designers a programming tool - HTML authors are normally not programmers, but JavaScript is a scripting language with a very simple syntax Almost anyone can put small "snippets" of code into their HTML pages
JavaScript can put dynamic text into an HTML page - A JavaScript statement like this: document.write("<h1>" + name + "</h1>") can write a variable text into an HTML page
JavaScript can react to events - A JavaScript can be set to execute when something happens, like when a page has finished loading or when a user clicks on an HTML element
JavaScript can read and write HTML elements - A JavaScript can read and change the content of an HTML element
JavaScript can be used to validate data - A JavaScript can be used to validate form data before it is submitted to a server. This saves the server from extra processing
JavaScript can be used to detect the visitor's browser - A JavaScript can be used to detect the visitor's browser, and - depending on the browser - load another page specifically designed for that browser
JavaScript can be used to create cookies - A JavaScript can be used to store and retrieve information on the visitor's computer