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 ECMAScript 5 in 2011 are being added to the site where they are supported by the latest version of all popular browsers. 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.

A few examples of what we can expect from EcmaScript 6 are also included in their own section so you can see the direction that JavaScript is moving in - even though it will probably be quite a while before we can use those commands.

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.

Open A Window

Early browsers didn’t have tabs and so could only opwn one web page at a time. You had to spawn another browser window when you wanted to display a new page that didn’t overwrite the existing one. Browsers now are far more flexible allowing multiple pages to be displayed within the one browser window using […]

location

We can both retrieve information about the address of the current page displayed in the browser and tell the browser to load a different page using the location object.

pushState

Many web pages now use JavaScript to apply numerous changes to the existing web page rather than continually downloading new pages. This means that where the history used to be able to track what was displayed in the browser, you can now have one web page that passes through a number of different states as […]

history

The browser keeps track of the last so many pages visited in the browser in a history list. JavaScript provides the history object which provides very limited access to the list in that you can tell how many entries are in the list and reload any page in the list but cannot read any of […]

postMessage

Where the web pages are on completely different domains you need to add specific Javascript on both domains in order to allow communication between them in modern browsers. The postMessage command is a relatively new addition to JavaScript and older browsers do not allow communication between different domains at all.

This site is © copyright Stephen Chapman - Felgall Pty Ltd 2011-2015.

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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.