What values exists for the XmlHttpRequest.readyState field, and what do they mean?
When is it appropriate to access, or use the other fields within the XmlHttpRequest object? The most important field is the readyState field. Once a value of 4 (i.e., complete) is received, then the next most important field is status. The value of status will be the same as the HTTP Status Code values When should AJAX NOT be used? It would not be appropriate to use AJAX when the “answer/result” can be determinded by the client. Generally, the purpose of AJAX is to submit a short request to the server, and process the response in such a way as to add value to the currently displayed page. It would also not be appropriate to use AJAX when the magnitude of the response is such that it would be easier, and more clear to redisplay the page. What objects are used by AJAX programs? The most bovious / correct answer would be “XmlHttpRequest”. However, personally, I would seriously consider someone who discussed the use of the callback routine, and most specifically “the response” as “objects”
