Question

Consider this code:

// Creating an empty object, without inheriting (binding) to any prototype
var human = Object.create(null); 
human.firstName = 'Saeed';
human.lastName = 'Neamati';

Now, I want to add a fullName property to this object, which returns the firstName + ' ' + lastName of the object.

Using object literal notation, I can simply write a getter function this way:

var human = {  
   firstName: 'Saeed',
   lastName: 'Neamati',
   get fullName() {
       return this.firstName + ' ' + this.lastName;
   }   
}

But I can’t figure out how to attach a getter property to an object, which is already built somewhere else.

Answer 1

You can use Object.defineProperty

Object.defineProperty(<object>, <property-name>, <descriptor>);

Where <descriptor> can be something like:

// from the example:
{ value: 0x9f91102,   
  get: function() { return 0xdeadbeef; } }