Not everyone who accesses your web pages will have a browser that supports JavaScript. Of those using a browser that does support JavaScript some will have JavaScript turned off for a variety of reasons. For your page to be accessible to all of your visitors it must still be useable for those visitors without JavaScript. In addition to this there will probably be a small percentage of your visitors who are still, for one reason or another, using really old web browsers that do not understand the modern web standards. We need to ensure that these visitors too will be able to use your site.
Being able to use the site does not mean that we need to have the site look and function the same way for all of these visitors in the same way it does for those visiting using a modern standards compliant web browser with JavaScript enabled. What it means is that we need to ensure that those visitors will at least have access to read the content of our page even if it doesn’t look the way we would like it to look. It means that any forms should have server side processing attached to them that permits them to at least provide minimal functionality by using server side processing to handle the content and reload the page. It means that the stylesheet and JavaScript enhance the appearance and behaviour of the web page rather than being required in order for the page to be usable at all.
In order to keep the code to a manageable size any server side processing that would be required to make our pages accessible without the JavaScript has been omitted from most of the scripts in this book and it is assumed that if you decide to use these scripts in a live web page that the necessary server side processing to make the page accessible to all visitors will be added.
There are a number of instances where the way that you code your HTML in the first place and the way that you add your JavaScript to that HTML will make the page accessible to all of your visitors without requiring server side processing. It is this aspect of JavaScript coding that we are going to consider next.
