Francis John Thottungal - JavaScript: For Beginners

JavaScript is a language for the world wide web. All websites use hyper text markup language(html) as the base for making a website. There are pages that are written in more advanced languages such as ASP, PHP, Python etc but the base still remains html. The hypertext markup language had limitations and these limitations are addressed by several languages including JavaScript.

Languages such as ASP, PHP, Python etc allow a website to interact with servers and external files when needed. They bring in a dynamism with relation to the server and external objects. Thus when a form is required to be filled and its details have to be saved these languages come into play.

JavaScript on the other hand like html is a client side language that makes the web pages lively. Floating surveys, greetings, interactive forms which has certain life to it, light weight games etc are some of its functions on the website.

It is possible to have a website without JavaScript. However, when it comes interactivity, friendliness, dynamism neither html nor some of the languages mentioned can beat JavaScript.

The basic requirement for understanding or using JavaScript is some background in html or hypertext markup language.

The following points are the advantages of JavaScript:

Less server interaction: JavaScript can be used validate user input before sending the page off to the server.

Immediate feedback to the visitors: JavaScript can help users of a webpage with info immediately without server connection.

Increased interactivity: Messages and dynamism can be added when mouse moves over parts and objects of a webpage.

Richer interfaces: Drop down menus etc can help the user to have a rich experience at the webpage.

JavaScript is an interpreted language which is lightweight and makes an otherwise static page made through html into something dynamic.

Before we start:

JavaScript can be run on all standard browsers in the market as long as it is enabled in the browser being used.

So find the browser that is on the computer and see the following:

Internet Explorer

Follow Tools -> Internet Options from the menu.

Select Security tab from the dialog box.

Click the Custom Level button.

Scroll down till you find the Scripting option.

Select Enable radio button under Active scripting.

Finally click OK and come out.

Firefox

Open a new tab -> type about: config in the address bar.

Find the warning dialog. Select Ill be careful, I promise!

Find the list of configure options in the browser.

In the search bar, type JavaScript. Enabled.

Find the option to enable or disable JavaScript by right-clicking on the value of that option -> select toggle.

Google Chrome

Click the Chrome menu at the top right hand corner of your browser.

Select Settings.

Show advanced settings at the end of the page.

Under Privacy section, click the Content settings button.

In the "JavaScript" section, select "Do not allow any site to run JavaScript" or "Allow all sites to run JavaScript (recommended)".

For other browsers please check their respective help sections.

The tools needed to JavaScript is the program notepad or similar editor and a browser. Initially an internet connection may not be required but having a connection on the computer can greatly help in more advanced programming that one will make down the line.

The JavaScript will be part of the html website. It could be encapsulated into pages where there is a mix of html and other languages. However, the examples in this book will be largely with html code.

Coding is best understood or appreciated when typed or written, therefore when learning JavaScript from this book write the code in to your favorite editor and check their working.

Many standard software packages such as Dreamweaver or Frontpage or Homesite among others are available for writing JavaScript but there is really no need for all these and when learning a language, the first time it is best to do it from scratch.

Few other aspects of JavaScript are:

1. It is case sensitive.

2. Semicolons are optional after statements. However, most programmers are used to putting this so do expect it in the examples in this book.

3. JavaScript ignores spaces, tabs, and newlines that appear in the programs. Therefore, spaces, tabs, and newlines can be used freely in a program to make it presentable and readable.

. Any text between a // and the end of a line is treated as a comment. Any text between the characters /* and */ is used for large comments. JavaScript also recognizes .

This book will use the C style approach of // for single comments and /* */ for larger comments.