AJAX - The Complete Reference

344 Part II: Developing an Ajax Library^

being received, the data being consumed, a retry occurring, or an error happening. A few

ideas of such changes are shown here:

An example to explore such indications can be found at http://ajaxref.com/ch8/

detailedprogress.html. As you inspect it, note the changes introduced to the AjaxTCR

library progress features discussed in Chapter 5. In order to allow for more granular

progress information, the statusIndicator object found in the options object has been

extended, as shown in Table 8-1.

In the case of very long network transactions, such as a large file upload or some long

running query, it is likely a good idea to provide some ongoing status. In Chapter 2, we

presented a basic file upload example using iframes, as XHRs generally cannot be used for

file uploading. While some of the examples include a progress bar like the previous

animated GIF based progress indicators, they did not provide any real indication of upload

progress. However, with a bit more work, it is possible to make a real progress bar by

simultaneously issuing extra requests to monitor the status of the upload and update the

progress bar, or by setting an appropriate message about the upload status. As an example,

the following is a form that would be used to upload a file.

<form enctype="multipart/form-data" name="requestForm" method="POST"

target="uploadresult">

Extended Status Indicator Properties Description

statusIndicator.progress.text Set to a string to display during all

unspecified aspects of a request.

statusIndicator.progress.imgSrc Set to a URL of the image to show in

all unspecified aspects of a request.

statusIndicator.progress.sending.text

statusIndicator.progress.sending.imgSrc

Text or images can be set to display

for the sending portion of a request.

statusIndicator.progress.receiving.text

statusIndicator.progress.receiving.imgSrc

Text or images can be set to display

for the receiving portion of a request.

statusIndicator.error.text

statusIndicator.error.imgSrc

Text or images can be set to display

when an error occurs.

statusIndicator.retry.text

statusIndicator.retry.imgSrc

Text or images can be set to display

when a retry occurs.

TABLE 8-1 Extensions to AjaxTCR statusIndicator Object