Object.getOwnPropertyDescriptors()

obj

The object for which to get all own property descriptors.

An object containing all own property descriptors of an object. Might be an empty object, if there are no properties.

This method permits examination of the precise description of all own properties of an object. A property in JavaScript consists of either a string-valued name or a Symbol and a property descriptor. Further information about property descriptor types and their attributes can be found in Object.defineProperty().

A property descriptor is a record with some of the following attributes:

value

The value associated with the property (data descriptors only).

writable

true if and only if the value associated with the property may be changed (data descriptors only).

get

A function which serves as a getter for the property, or undefined if there is no getter (accessor descriptors only).

set

A function which serves as a setter for the property, or undefined if there is no setter (accessor descriptors only).

configurable

true if and only if the type of this property descriptor may be changed and if the property may be deleted from the corresponding object.

enumerable

true if and only if this property shows up during enumeration of the properties on the corresponding object.

Whereas the Object.assign() method will only copy enumerable and own properties from a source object to a target object, you are able to use this method and Object.create() for a shallow copy between two unknown objects:

Object.create(
  Object.getPrototypeOf(obj),
  Object.getOwnPropertyDescriptors(obj),
);

A typical way of creating a subclass is to define the subclass, set its prototype to an instance of the superclass, and then define properties on that instance. This can get awkward especially for getters and setters. Instead, you can use this code to set the prototype:

function superclass() {}
superclass.prototype = {
  // Define the superclass constructor, methods, and properties here
};
function subclass() {}
subclass.prototype = Object.create(superclass.prototype, {
  // Define the subclass constructor, methods, and properties here
});

• Polyfill of Object.getOwnPropertyDescriptors in core-js
• Object.getOwnPropertyDescriptor()
• Object.defineProperty()