Cloning Non enumerable properties in javascript

Question

I have all non - enumerable properties in object, I want to clone that object.

My problem non-enumerable properties are not getting cloned.

Take below example

 Object.defineProperty(this, 'prop', {
        get: function () {
            return prop;
        },
        set: function (value) {
            prop= value;
        }
    });

   Object.defineProperty(this, 'newprop', {
        get: function () {
            return newprop;
        },
        set: function (value) {
            newprop= value;
        }
    });

For example I have above two properties in my object doing clone using following methods, my properties are not getting cloned I believe it is because they are non - enumerable.

   var newObject = $.extend({},oldObject);
   var newObject= Object.assign({},oldobject);

How do I copy non-enumerable properties in javascript.

Answer 1

If one or more properties aren't enumerable, how do you want to auto-magically enumerate them?

Since you know their names, you should do something like this:

var sourceObj = this;
var targetObj = {};

["prop", "otherProperty"].forEach(function(property) {
    targetObj[property] = sourceObj[property]; 
});

Or you can build the whole property name array whenever you define a non-enumerable property:

   var propertyNames = [];

   Object.defineProperty(this, 'newprop', {
        get: function () {
            return newprop;
        },
        set: function (value) {
            newprop= value;
        }
    });
    propertyNames.push("newprop"); // <---


   Object.defineProperty(this, 'newprop2', {
        get: function () {
            return newprop;
        },
        set: function (value) {
            newprop= value;
        }
    });
    propertyNames.push("newprop2"); // <---

propertyNames.forEach(function(property) {
    targetObj[property] = sourceObj[property]; 
});

Alternate approach: Object.getOwnPropertyNames

The Object.getOwnPropertyNames() method returns an array of all properties (enumerable or not) found directly upon a given object.

Maybe this is the best approach. Object.getOwnPropertyNames gets the name of own object's properties either if they're enumerable or not. That is, you can avoid building the whole propertyNames array, and this approach should be fine with you because you said that all properties aren't enumerable:

var sourceObj = this;
var targetObj = {};    

Object.getOwnPropertyNames(sourceObj).forEach(function(property) {
    targetObj[property] = sourceObj[property]; 
});

Answer 2

You can use Object.defineProperties and Object.getOwnPropertyDescriptors() function

The Object.defineProperties() method defines new or modifies existing properties directly on an object, returning the object.

The Object.getOwnPropertyDescriptors() method returns all own property descriptors of a given object.

So, you can add the properties of the original object into an empty object, as follow

var source_obj = this
var cloned_obj = Object.defineProperties({}, Object.getOwnPropertyDescriptors(source_obj));