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From: Cezary Tomczyk <cezary.tomczyk@gmail.com>
Newsgroups: comp.lang.javascript
Subject: Re: Cloning an object
Date: Thu, 5 Jul 2018 10:00:53 +0200
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Xref: csiph.com comp.lang.javascript:35349

On 04/07/2018 23:25, Thomas 'PointedEars' Lahn wrote:
[...]
> Deep copies are easy with recursion.  In this case, tested in
> navigator.userAgent === "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36
> (KHTML, like Gecko) Chrome/57.0.2987.98 Safari/537.36":
> 
>    function clone (obj, deepCopy)
>    {
>      const CLONE = Object.create(Object.getPrototypeOf(obj));
>      
>      Object.getOwnPropertyNames(obj).forEach((name) => {
>        const DESC = Object.getOwnPropertyDescriptor(obj, name);
> 
>        if (deepCopy)
>        {
>          /* FIXME: Standardize Object.isObject() */
>          if (("value" in DESC)
>              && (typeof DESC.value == "object")
>              && (DESC.value != null))
>          {
>            DESC.value = clone(DESC.value);
>          }
>        }
> 
>        Object.defineProperty(CLONE, name, DESC || {});
>      });
> 
>      return CLONE;
>    }
> 
>    const ORIG = {foo: {bar: "baz"}};
>    const CLONE = clone(ORIG, true);
> 
>    /* "baz" */
>    console.log(CLONE.foo.bar);
> 
>    CLONE.foo.bar = 42;
> 
>    /* 42 */
>    console.log(CLONE.foo.bar);
> 
>    /* "baz" */
>    console.log(ORIG.foo.bar);
> 
> See also jsx.object.clone() in JSX:object.js (not yet adapted to ES 6, but
> with more options):
> 
> <https://github.com/PointedEars/JSX/blob/master/object.js#L601-L695>

It passes for simple objects, but if the property has a value as an 
array or Date object then it doesn't work. But I think above solution 
can be enhanced to support it.

-- 
Cezary Tomczyk
http://www.ctomczyk.pl/
https://www.aslint.org/