AJAX - The Complete Reference

Chapter 2: Pre-Ajax JavaScript Communications Techniques 45

PART I

var average = xmlDoc.getElementsByTagName("average")[0].firstChild.nodeValue;

var total = xmlDoc.getElementsByTagName("votes")[0].firstChild.nodeValue;

var rating = xmlDoc.getElementsByTagName("rating")[0].firstChild.nodeValue;

/* get target div */

var target = document.getElementById(commObject.ui.outputTarget);

/* indicate vote was made and show result */

target.innerHTML = "Thank you for voting. You rated this a <strong>" +

rating + "</strong>. There are <strong>" + total + "</strong> total votes. The

average is <strong>" + average + "</strong>. You can see the ratings in the

<a href='http://ajaxref.com/ch2/ratings.txt' target='_blank'>ratings file</a>.";

}

This discussion should not be read as a criticism of XML, but rather a serious indication

that you need to choose the right transmission and response data format for the job. Given

the importance of such a decision, Chapter 4 is devoted solely to this topic.

File Uploads with Iframes

One aspect of iframes that will certainly come back later in the book is their involvement in

file uploads. In a standard Web browser, it is not possible to script the <input type="file"

/> field to read its contents. Before you get annoyed, consider that this really is a good thing

FIGURE 2-7 Iframes can send and receive almost anything.