AJAX jQuery PHP Return Value

Question

I am new to AJAX and am kind of confused by what PHP passes back to the jQuery. So you have an AJAX function like this:

 $.ajax({ url: '/my/site',
     data: {action: 'test'},
     type: 'post',
     success: function(output) {
                  alert(output);
              }
 });

(I took this from ajax another StackOverflow page.)

But on various other resources they will have the success section look like this:

 success: function(data) {functionfoocommandshere}

I am just confused as to what dictates the naming of this variable? If the PHP ultimately echoes an array:

  echo $myVar;

How can I get this from the AJAX?

Answer 1

An Ajax-Requests fetches a whole site. So you'll not get any data in variables, but the whole site in the data-parameter. All echos you made together will be in this parameter. If you want to retrieve an array, you should transform it to json before.

echo json_encode($myArray);

Then you can receive it via Ajax in this way

$.ajax({ url: '/my/site',
 data: {action: 'test'},
 dataType: 'json',
 type: 'post',
 success: function(output) {
              alert(output);
          }
 });