Conventional way of searching: Type the search phrase, click Search, wait for the Search results to load, scan the results, refine phrase, click Search again…

Conventional way of emailing: Click New Mails, wait for page to load, Read Mail 1, click Next Mail, wait for page to load…

Enter Google – with GMail and Google Suggest. The ‘wait’ didn’t exist for me anymore. GMail is such a divergent way from the usual hyperlinked way of displaying mails that it blew me the first time I tried it. Once I started digging deeper into it, words like JavaScript, DOM and the acronym AJAX were thrown at me. As I discovered the promise of AJAX and its applications, it suddenly dawned on me that the World Wide Wait (!) need not be the case every time you use a web application like Email or Search.

AJAX, is an acronym for Asynchronous JavaScript and XML, coined to describe a new methodology to wield JavaScript, HTML, DOM and XMLHTTPRequest.

The traditional Request Response model which is used when a user clicks on a New Mail or Search button has no code in the client side and each such click involves a round trip to the server. This was very slow and god save the user who wants an email id of John with any popular web mail provider – it would involve atleast 5 button clicks as you try out various combinations and the total time taken would be anywhere around 5 mins to get a unique user id.

But with AJAX, as you type J-O-H-N, the user will see a message that it is not available and will be displayed alternatives and can continue typing and choose the user id, within a few seconds. The reason – there are no round trips each and every time the user clicks on Submit. These are replaced by asynchronous calls to the Server based on any user action.

Taking our problem of finding an email id for John, all one would have to do is place a request (XMLHTTPRequest) on the Lost Focus (JavaScript) event of the Text Box (HTML) which holds the user id. As you keep typing, your request is processed by the server each time and you can display the results to the user in a small area of the page (DOM).

Of course, there are quite a few disadvantages with this approach, the principal one being that JavaScript can be disabled and it usually is by users who are security conscious. Another one is that quite a bit of code has to be written in the Client side and this can easily compromise the security of a particular application.

The tradeoff here should be between convenience and security. Quite a few users are ready to live with JavaScript enabled for specific sites like GMail since the user experience is radical. For those who think that JavaScript is dead, AJAX could be its resurrection.

The essay which started it all for me, by Adaptive Path.

Wikipedia has quite a good writeup on this technology and lots more links.

This entry was posted on Thursday, August 18th, 2005 at 12:08 pm and is filed under Javascript. You can leave a response, or trackback from your own site.