How do I clone a JavaScript class instance?

Question

How do I clone a JavaScript class instance?

I tried the normal jQuery extend, but that just returns a vanilla object. I have looked through many other answers on sta

Answer 1

This will create a copy of an object with the same prototype (class) and same own properties (including enumerability/writability/getters/setters etc):

function clone(obj) {
  return Object.create(
    Object.getPrototypeOf(obj), 
    Object.getOwnPropertyDescriptors(obj) 
  );
}

(see here)

It doesn't necessarily work well for builtin objects. For example Array.isArray(clone([])) is false, and clone(function () {})() says it is not a function, but for user created objects (either class instances or object literals) it works fine.

To do a deep clone, you will have to loop over the property descriptors and clone the values recursively:

function deepClone(obj) {
  if (obj === null || typeof obj !== "object")
    return obj
  var props = Object.getOwnPropertyDescriptors(obj)
  for (var prop in props) {
    props[prop].value = deepClone(props[prop].value)
  }
  return Object.create(
    Object.getPrototypeOf(obj), 
    props
  )
}