Thank you for your reply. I have fixed this issue by adding "header("Content-type: application/javascript");" in the bottom of domain pricing.php file.
Everthing is working fine but when click on "Countinue" button showin following error in my developer console. Let me know how to fix it.
"Uncaught TypeError: n.showInputError is not a function
at HTMLFormElement.<anonymous> (scripts.min.js?v=41606b:2:10947)
at HTMLFormElement.dispatch (scripts.min.js?v=41606b:2:29999)
at $.handle (scripts.min.js?v=41606b:2:26701)"
Screenshot attached.