Question

Some projects use Object.create() or Object.defineProperties() function. I wonder is is recommended? Whats the difference between

x = Object.create(null); 

vs

x = {}

And

x = {}
x.__proto__.hello = function() { 
    console.log("hello"); 
}

vs

x = Object.create(null);
Object.defineProperty(x, "hello", { 
    value: function() { 
        console.log("hello"); 
    } 
});

defineProperty/create seems very verbose and long to me. When/Why do I use them? Perhaps the good might be to enforce getters/setters/overriding properties?

Answer 1

There is a huge difference. Have a look at the docs!

• Object.create does create an Object that inherits from the first argument, null in your case. In contrast, {} – or new Object() – creates a new object that inherits from Object.prototype.
• __proto__ is non-standard and should not be used. However, in your case you just do Object.prototype.hello = function() {…};. Never extend that object with enumerable properties, never ever!
• Object.defineProperty does define a property on an object with a special descriptor object. The enumerable, configurable and writable attributes default to false, which means that you wont be able to delete x.hello for example, or assign any other value.

Your first snippet creates a plain object, which inherits a hello method from Object.prototype, while your second snippet creates an object inheriting from nothing and having a non-editable hello property. I don’t see much relatedness.