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) {
}
});
}
});