Split First name and Last name using JavaScript

You should use the String.prototype.split() method:

'Paul Steve Panakkal'.split(' '); // returns ["Paul", "Steve", "Panakkal"]

You can use it this way:

'Paul Steve Panakkal'.split(' ').slice(0, -1).join(' '); // returns "Paul Steve"
'Paul Steve Panakkal'.split(' ').slice(-1).join(' '); // returns "Panakkal"

So in common:

var firstName = fullName.split(' ').slice(0, -1).join(' ');
var lastName = fullName.split(' ').slice(-1).join(' ');