How to pass javascript variable to php using ajax

Question

I am trying to pass a javascript variable which I get when a button is clicked to php and then run a mysql query. My code:

function ajaxCall(nodeID) {
 $.ajax({
         


        

Answer 1

There's a bit of confusion here, the success value stores a callback that gets called when the Ajax call is successful. To give you a simple example, let's say you have an Ajax call like this:

function ajaxCall(nodeID) {
    $.ajax({
      type: "POST",
      url: "tree.php",
      data: {activeNodeID : nodeID}, 
      success: function(data) {
        console.log(data.my_message); 
      }
    });

This calls a PHP page called tree.php. In this page you do some computation and then return a value, in this case as JSON. So the page looks like this (note that I'm keeping it simple, you should validate input values, always):

$v = $_REQUEST['activeNodeID'];
$to_return = "the value sent is: " . $v;
return json_encode(array('my_message' => $to_return));

This simple PHP page returns that string as a JSON. In your javascript, in the specified callback (that is success), you get data as an object that contains the PHP's $to_return value. What you have written does not really makes sense since PHP is a server language and cannot be processed from the browser like JavaScript.