DHTML for Not Yet Techies 2

DHTML changes the HTML of the page by using one of the established scripting languages. This is mainly JavaScript, but could be VBScript in Internet Explorer. (Netscape doesn’t support VBScript). DHTML requires browsers capable of doing this. It really became possible only with the introduction of Netscape 4.0+ and Internet Explorer 4.0+. Earlier browsers did not provide the same access to changing the hypertext markup of the DOM.

The HTML in the web page changes when some event occurs. This means when the web site visitor does something. This could be running a mouse over a picture or a text, loading a page, clicking on part of a form, submitting a form etc. This is done through the scripting language, and controlled by DHTML.

You have probably seen examples of this. Maybe you have used the mouse to run the cursor over a picture, and it changed, or a small box of text appeared. That was probably JavaScript in action. A small but common use of DHTML.

Data binding is an aspect allowing for the web site to obtain information from the server, such as a from a database, and use it within an HTML page. For instance, you order something and you get an acknowledgement page that has your name written on it. Maybe you didn’t think about at the time, but for the web site to place your name into a page took some form of scripting. Web pages couldn’t do that back when I started browsing the Web in 1995.

The complicated part of DHMTL comes from the differences between Netscape and Explorer. Both of them implement it in different ways.

As mentioned, Microsoft’s DOM allows for many more aspects of the page to changed than does Netscape. Also, Microsoft’s implementation of DHTML allows for a lot of multimedia elements that were previously available only through plug-ins.

Netscape’s implementation of DHTML depends a lot on its use of layers – placing one HTML element on top of each other. This can be very useful to web designers who like to get very artistic and fancy and win awards as the Cool Web Site of the Moment.

You can also embed fonts with Netscape. This means that you can put fonts on your website that the web site visitor does not have already installed on their computer. Most of us are satisfied using the common and popular fonts that are almost everyone’s computer but – again – they are many web site designers who want to be very artistic. 

They’re bored with the common fonts. They have long wanted to use fancy fonts, but could not, because they are not installed on most people’s computer. Your web browser can display only the type fonts installed on your computer. If it comes across a web site using a font that it does not have access to, it will either switch to a default such as New Times Roman or not display anything at all.

Netscape’s DHTML is based more on style sheets, especially what it calls JavaScript style sheets, where the HTML elements are changed through JavaScript.

DHTML is continuously changing. It’s a headache for computer job web developers on the Internet, because they must design web sites that look good in BOTH Netscape and Explorer. The future of it will depend in large part on the outcome of the "browser war" between Netscape and Explorer. The latest information is that Explorer now has close to 2/3s of the market, so it is clearly pulling ahead. However, nobody knows the final outcome of the government’s lawsuit against Microsoft.

What you will want to do with DHTML will of course depend a lot on what you want to do with your web site. If you want to impress your young friends with the latest "cool, gee whiz" special effects, you will use Dynamic HTML a lot differently than a business trying to sell high class living room furniture.

There is no doubt that a practical how-to knowledge of DHTML is required for a computer career designing web sites for today’s Internet web browsers.

Next: VRML