Changing content on the fly using JavaScript

Introduction

One of my favorite uses of JavaScript, and I guess more specifically, DHTML, is to change content on the fly. Using just a few lines of scripting, I can do away with the slow downloading Java and Flash, and change text even after the page has loaded. I write this tutorial based on the assumption that you have at least some working knowledge of JavaScript.

Changing text requires 3 different techniques, depending on the browser. If you're like me, you favor Internet Explorer 5, but the point is that there are always people using other browsers, so we must address them all.

Details

Let me first introduce a simple text which I will base my explanations on changing text using:

<div ID="testing">MSNBC.com</div>

In Internet Explorer 4 or above, the script to change the above text is:

document.all.testing.innerHTML = "A very cool site!"

I access the text's ID, which tells the script which text I wish to change. Then I use the property innerHTML, which allows me to change this text to another.

In Netscape 6, the idea to alter a text is very similar, except in the precise syntax:

document.getElementById("testing").innerHTML = "A very cool site!"

Interesting to note is that Internet Explorer 5 also supports this method of changing text. If you don't care about IE4, this one line is sufficient to cover both IE5 and NS6.

Finally, we have the dreaded Netscape 4, which surprising is still more popular than NS6. To change text in this browser, I must actually embed the text using a different set of tags (from the DIV). The tags required is:

<ilayer name="testing"><layer name="testing2">MSNBC.com</layer></ilayer>

Once the proper tags are setup, I can change its text in Netscape 4 using:

document.testing.document.test2.document.write("A very cool site!")
document.testing.document.test2.document.close()

Awk! Yes, it's quite messy, but that's the only route to NS4's heart!

Conclusion

Many interesting and useful applications can be created by dynamically altering text. I can create a message scroller that changes messages every few seconds, a text that changes when I move my mouse over it, or even an image slide show with a corresponding description beneath it.

If you're looking for working examples of changing text on the fly, a good place to start is Dynamic Drive. Well, that's it for now. Visit my site if you have any suggestions for new tutorials I can contribute.