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Groups > comp.lang.javascript > #35353

Re: Cloning an object

From Cezary Tomczyk <cezary.tomczyk@gmail.com>
Newsgroups comp.lang.javascript
Subject Re: Cloning an object
Date 2018-07-05 20:37 +0200
Organization csiph.com Internet News Service
Message-ID <phloi4$kb2$1@csiph.com> (permalink)
References (3 earlier) <9909bfec-c6e7-2a4a-2a54-ec9f271691c8@PointedEars.de> <phdcst$1hro$1@csiph.com> <4395113.31r3eYUQgx@PointedEars.de> <phkj7m$2ugj$1@csiph.com> <506b67da-b086-3d0e-5985-d0f8214da432@PointedEars.de>

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On 05/07/2018 19:49, Thomas 'PointedEars' Lahn wrote:
> Cezary Tomczyk wrote:
> 
>> On 04/07/2018 23:25, Thomas 'PointedEars' Lahn wrote:
>>>     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;
>>>     }
>>> […]
>>
>> It passes for simple objects, but if the property has a value as an
>> array or Date object then it doesn't work.
> 
> I agree regarding Date instances, but where is the problem with Array
> instances?

It doesn't create a real Array copy. Try clone following object:

var o = {
   a: 1,
   b: [
     {
       test: 'test'
     }
   ]
};

var cloned = clone(o);

o.b[0].test = 'something';

expect(cloned.b[0].test).toBe('test');

This test doesn't pass. Basically, modifications on original object 
should not modify cloned object.

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

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Thread

Recording changes to an object Andrew Poulos <ap_prog@hotmail.com> - 2018-06-21 15:54 +1000
  Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 01:47 -0700
  Re: Recording changes to an object Ben Bacarisse <ben.usenet@bsb.me.uk> - 2018-06-21 17:01 +0100
    Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 09:48 -0700
      Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-06-22 09:58 +0100
  Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-21 21:03 +0200
    Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 16:25 -0700
    Re: Recording changes to an object Andrew Poulos <ap_prog@hotmail.com> - 2018-06-22 09:34 +1000
      Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 17:02 -0700
        Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 18:03 -0700
        Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-06-22 10:06 +0100
          Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-22 02:21 -0700
            Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-06-22 18:31 +0100
              Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-22 20:16 -0700
      Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-22 02:23 +0200
        Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 17:31 -0700
      Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-22 02:55 +0200
        Re: Recording changes to an object Andrew Poulos <ap_prog@hotmail.com> - 2018-06-22 12:37 +1000
          Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-22 02:23 -0700
            Re: Recording changes to an object Jake Jarvis <pig_in_shoes@yahoo.com> - 2018-06-22 14:35 +0200
              Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-22 05:57 -0700
                Re: Recording changes to an object Mickey Finn <mfinn@gmail.com> - 2018-06-22 15:43 -0300
              Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-22 13:51 +0200
                Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-22 06:04 -0700
                Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-06-22 18:33 +0100
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-24 14:36 +0200
                Re: Recording changes to an object "Mark-" <nospam@mapson.xyz> - 2018-06-24 13:56 +0000
                Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-06-25 10:06 +0100
                Re: Recording changes to an object Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-06-25 02:40 -0700
                Re: Recording changes to an object Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-06-25 02:47 -0700
                Re: Recording changes to an object Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-06-25 02:51 -0700
                Re: Recording changes to an object Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-06-25 02:54 -0700
                Re: Recording changes to an object Jonas Thörnvall <jonas.thornvall@gmail.com> - 2018-06-25 02:58 -0700
                Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-06-25 19:26 +0100
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-30 19:47 +0200
                Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-07-01 10:56 +0100
            Re: Recording changes to an object Andrew Poulos <ap_prog@hotmail.com> - 2018-06-23 17:19 +1000
              Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-23 00:51 -0700
                Re: Recording changes to an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-06-23 11:27 +0100
                Re: Recording changes to an object Andrew Poulos <ap_prog@hotmail.com> - 2018-06-23 20:59 +1000
                Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-23 05:51 -0700
    Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-06-30 19:43 +0200
      Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-01 15:22 +0200
        Re: Recording changes to an object Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2018-07-02 16:29 +0200
          Cloning an object (was: Recording changes to an object) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-04 23:25 +0200
            Re: Cloning an object Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2018-07-05 10:00 +0200
              Re: Cloning an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-05 19:49 +0200
                Re: Cloning an object Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2018-07-05 20:37 +0200
                Re: Cloning an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-05 23:35 +0200
                Re: Cloning an object Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2018-07-05 23:54 +0200
                Re: Cloning an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-06 00:32 +0200
                Re: Cloning an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-06 00:24 +0200
                Re: Cloning an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-07-06 18:48 +0100
                Re: Cloning an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-06 23:51 +0200
                Re: Cloning an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-07-07 15:51 +0100
                Re: Cloning an object Julio Di Egidio <julio@diegidio.name> - 2018-07-07 08:39 -0700
                Re: Cloning an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-07-09 10:20 +0100
                Re: Cloning an object Julio Di Egidio <julio@diegidio.name> - 2018-07-09 02:35 -0700
                Re: Cloning an object Julio Di Egidio <julio@diegidio.name> - 2018-07-09 02:41 -0700
                Re: Cloning an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-08 12:20 +0200
                Re: Cloning an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-07-08 14:38 +0100
                Re: Cloning an object Julio Di Egidio <julio@diegidio.name> - 2018-07-08 13:10 -0700
                Re: Cloning an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-07-09 09:48 +0100
                Re: Cloning an object Julio Di Egidio <julio@diegidio.name> - 2018-07-09 02:28 -0700
                Re: Cloning an object Julio Di Egidio <julio@diegidio.name> - 2018-07-09 02:38 -0700
                Re: Cloning an object John G Harris <niam@jghnorth.org.uk.invalid> - 2018-07-09 19:11 +0100
      Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-02 21:01 -0700
        Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-05 00:32 +0200
          Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-04 19:23 -0700
            Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-05 06:38 +0200
              Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-04 23:21 -0700
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-05 09:25 +0200
                Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-05 07:44 -0700
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-05 19:35 +0200
                Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-06 12:59 -0700
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-06 23:22 +0200
                Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-07 12:45 -0700
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-08 11:13 +0200
                Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-07-08 05:03 -0700
                Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-08 13:42 -0700
                Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-07-08 13:46 -0700
                Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-08 13:41 -0700
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-09 00:35 +0200
                Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-10 01:03 -0700
                Re: Recording changes to an object Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2018-07-10 20:50 +0200
                Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-07-10 16:09 -0700
  Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-06-21 15:09 -0700
    Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 16:30 -0700
      Re: Recording changes to an object "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2018-06-21 16:57 -0700
        Re: Recording changes to an object Julio Di Egidio <julio@diegidio.name> - 2018-06-21 17:01 -0700

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