Question

Giving the following example:

var animal= null;

$.post("ajax.php",{data: data}, function(output){
     animal = output.animal;
},"json");

alert(animal);

In principle I wanted the variable to return something outside the ajax function’s success callback and I declare it outside the post. However it is still returning “null”. What am I doing wrong?

Answer 1

The problem is the alert command is executing before the success function, because $.post is by definition asynchronous.

To do what you want, you have to use a synchronous request (the code will not execute before the request is over) like this:

 var animal = null;

 $.ajax({
        url: 'ajax.php',
        async: false,   // this is the important line that makes the request sincronous
        type: 'post',
        dataType: 'json', 
        success: function(output) {
                animal = output.animal;
             }
          );

  alert(animal);

Good luck!