how do i define the success and failure function of an ajax $.post?
If you need a failure function, you can't use the $.get or $.post functions; you will need to call the $.ajax function directly. You pass an options object that can have "success" and "error" callbacks.
Instead of this:
$.post("/post/url.php", parameters, successFunction);
you would use this:
$.ajax({
url: "/post/url.php",
type: "POST",
data: parameters,
success: successFunction,
error: errorFunction
});
There are lots of other options available too. The documentation lists all the options available.