Implementing Object.create allows for the creation and sharing of methods for each instance without compromising memory efficiency

Here's an example code snippet where I am trying to understand Object.create:

function Animal {}
var cat = new Animal();

I have a requirement to create 100 animals and add a method called saySomething() to the constructor. To achieve this, I add the method to the prototype so that it is created only once and every instance can access it:

Animal.prototype.saySomething = function(voice) {
       console.log(voice)
  }

Now, let's consider creating objects in a different way:

var Animal = {
   saySomething: function(voice) {
       console.log(voice)
  }
}

var cat = Object.create(Animal);
var dog = Object.create(Animal); 
...

The question arises - when I create objects like this, is the saySomething method created for each instance separately? How can I add this method to the Animal object in the same manner as before? It's a bit confusing for me at the moment. Please help!

Answer №1

It appears that the method is only created on the prototype. dog.__proto__.saySomething - is defined, indicating it is defined on the prototype

To confirm,

dog.hasOwnProperty('saySomething')
returns false, suggesting the property isn't enumerable or is defined on the prototype.

If you wish to add methods to your cat or dog and ensure only one copy of properties are created, you can simply add them to an instance and then call Object.create on the instance.


var Animal = {
   saySomething: function(voice) {
       console.log(voice)
  }
}

var cat = Object.create(Animal);
var dog = Object.create(Animal); 
cat.saySomething = function(){
    console.log('meow')
}; 
var catInstance = Object.create(cat);
catInstance.saySomething();  // 'meow'
typeof catInstance.__proto__.saySomething == "function"  // true

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