Introducing JavaScript

JavaScript has changed a great deal since it was first introduced but many sites still use outdated techniques. There are even lots of JavaScript tutorials on the web that show you how JavaScript should be written so that it can work in Netscape 2 rather than so that it will work in modern browsers. As a result there are many people who are writing what they think is JavaScript but where what they are producing is more suited to the 20th Century than to the 21st.

Beginners should work through all the basic examples prior to moving on to the other examples which cover separate aspects of JavaScript in more detail.

Most of the JavaScript examples here will work in IE5+, Opera7+ and all versions of Firefox, Safari and Chrome. Those commands introduced in ECMAScript5.1 in 2011 have been added (if I have missed any please let me know). Those commands introduced in ECMAScript2015 are currently being added (there are lots of them so it may take some time but then most current browsers do not yet support them all anyway). Where these new commands are not supported by IE8 or IE7 that information is included in the text since those two browsers might still have to many users for you to ignore. So few people using other browsers fail to keep their browser up to date that lack of support in older versions of other browsers will not have any significant affect.

There is a link to jsBin at the bottom right of all the pages. This site provides an easy way to test your JavaScript code online without needing to create an entire web page to run a simple test.


Once you understand the basic syntax of the core JavaScript language, it is time to move on to look at various aspects of the core language in more detail. We’ll start by working our way through the various objects built into JavaScript. Some of these objects are more useful than others. A couple are static […]

The Error Console

All browsers provide a JavaScript error console that will report information about any errors in your script. This is the first place to look to get information about scripts that do not work properly.

Testing Your JavaScript

Just as important as knowing how to write JavaScript is knowing how to test it. There is no point in writing JavaScript that doesn’t work at least in all the more popular browsers – which is why the list of tools mentioned at the start of the series suggested that you install a number of […]

A Starting Template

Creating new JavaScript (and HTML etc) files is always easier when you have a starting point. Here we look at some code to give us such a starting point for our scripts.

JavaScript Content Security

One consideration regarding web pages and JavaScript whether your page contains any JavaScript or not is the possibility of someone managing to inject JavaScript into your web page before it is delivered to someone else. If you have followed the examples so far you know how to keep your scripts separate from the HTML. This […]

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You are welcome to use any the example JavaScript from this site in the scripts for your site or any that you develop for others but may not use the longer example scripts that contain a copyright notice in any other way without permission.