Question

I want to have a javascript function such as this:

function isUsernameAvailable(username) {    //Code to do an AJAX request and return true/false if   // the username given is available or not } 

How can this be accomplished using Jquery or Xajax?

Answer 1

The big win when using AJAX is that it is asynchronous. You’re asking for a synchronous function call. This can be done, but it might lock up the browser while it is waiting for the server.

Using jquery:

function isUsernameAvailable(username) {     var available;     $.ajax({         url: 'checkusername.php',         data: {name: username},         async: false, // this makes the ajax-call blocking         dataType: 'json',         success: function (response) {             available = response.available;         }      });      return available; } 

Your php-code should then check the database, and return

{available: true} 

if the name is ok.

That said, you should probably do this asynchronously. Like so:

function checkUsernameAvailability(username) {     $.getJSON('checkusername.php', {name: username}, function (response) {         if (!response.available) {             alert('Sorry, but that username isn't available.');         }     }); }