jQuery Ajax Request inside Ajax Request

This is just an example. You may like to customize it as per your requirement.

 $.ajax({
      url: 'ajax/test1.html',
      success: function(data1) {
        alert('Request 1 was performed.');
        $.ajax({
            type: 'POST',
            url: url,
            data: data1, //pass data1 to second request
            success: successHandler, // handler if second request succeeds 
            dataType: dataType
        });
    }
});

For more details : see this

Call second ajax from 'complete'

Here is the example

   var dt='';
   $.ajax({
    type: "post",
    url: "ajax/example.php",
    data: 'page='+btn_page,
    success: function(data){
        dt=data;
        /*Do something*/
    },
    complete:function(){
        $.ajax({
           var a=dt; // This line shows error.
           type: "post",
           url: "example.php",
           data: 'page='+a,
           success: function(data){
              /*do some thing in second function*/
           },
       });
    }
});

Here is an example:

$.ajax({
    type: "post",
    url: "ajax/example.php",
    data: 'page=' + btn_page,
    success: function (data) {
        var a = data; // This line shows error.
        $.ajax({
            type: "post",
            url: "example.php",
            data: 'page=' + a,
            success: function (data) {
   
            }
        });
    }
});