Learning AJAX by example?

[BobMCT]

Seeing how there is liitle/no activity on the Ajax forum, I am reposting this here:

Gents;

I've been struggling with this for literally months and cannot seem to get a handle on it. I am a seasoned developer but not that familiar with js. I've spent the last several days (yes - many, many days over months) searching for examples and have found many but not what I believe would be a simple solid example.

I am trying to use the onchange attribute of an html <select> statement so the selected item will trigger a js script to communicate with a server via XMLHttpRequest then accept the returned content and populate a target select section.
I do have a working host module that returns a json encoded string with the desired content. In fact, here it is:

{"*A":"*ALL","C5":"Cash 5","L":"Classic Lotto","P3E":"Play 3","P3M":"Midday 3","P4E":"Play 4","P4M":"Midday 4","PB":"Powerball"}

I've played with many many variations of js code in my test php program/js content without success.

I am HOPING that someone here can reference a simple set of js scripts that will:

1) generate an XMLHttpRequest based on the value selected by the user on the first select/option set;

2) parse the returned json content and re-populate the target select/option set then enable the select itself.

Someone, somewhere must have this logic or at least know where to find good examples?

I do have several javascript books as well as access to much online js content. And, an example is worth a thousand words (or days in my case).

Thanks to ANYONE who can provide this example or a reference thereof.

B ponder

 

[vicvirk]

If you are indeed a seasoned developer, the tutorial at w3schools should be all you need...you must read through all of it, not just skim it and go to the pages/sections you need. Take the time (it takes under 1 hour) to read through it all and understand how it all works. Go through the examles and try them out...

http://w3schools.com/ajax/

--------
GOOGLE is a great resource to find answers to questions like "how do i..."

If you don't know exaclty what you want to do or what to search on, try Google Suggest:

http://www.google.com/webhp?complete=1&hl=en

--------
I have recently been semi-converted to ensuring all my code (well most of it) works in both javascript and non-javasc

 

[BobMCT]

Thanks, vicvirk;

It turns out my basic understanding of ajax was OK and I have already been through the w3schools tutorials. Using Firebug I was able to trace the issue to some invalid javascipt syntax which was causing failure AFTER the return and capture of the host response.

Thanks anyway.