Javascript : How to add getter to an existing object

Question

I can have a getter in a JavaScript object like this:

var member = {     firstName:"XYZ",      lastName:"zzz",      get fullName(){ return (this.firstName + ' ' + this.lastName); } } 

I can even add more properties on the fly, like this:

member.isGuest = true; 

But, is there any way we can add getters to an existing object? Something like this:

member.isGuest = get isGuest(){ return this.firstName=='Guest'; } 

Answer 1

try defineProperty

Object.defineProperty(member, 'isGuest', {   get: function() { return this.firstName=='Guest' } });