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Re: check for obj nested prop

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From Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups comp.lang.javascript
Subject Re: check for obj nested prop
Date Tue, 12 May 2020 09:28:31 +0200
Organization PointedEars Software (PES)
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Ben Bacarisse wrote:

> Thomas 'PointedEars' Lahn <PointedEars@web.de> writes:
>> Ben Bacarisse wrote:
>>> Andrew Poulos <ap_prog@hotmail.com> writes:
>>>> so I end up doing
>>>>
>>>> if (a && a.b && a.b.c && a.b.c.d)
>>> <cut>
>>>> Is there a way to get the check value of an object's nested property
>>>> without first having to test for all the ascendant properties?
>>> 
>>>   if (try {obj.a.b.c.d} catch {})
>>> 
>>> might do what you want.
>>
>> This is *obviously* syntactically invalid;
> 
> Yes, wishful thinking.  You'd need a function call and a return:
> 
>   if ( (()=>{ try {return obj.a.b.c.d} catch {} })() ) ...
> 
> which makes it rather clumsy.

It is not only clumsy, it is also not safe (and this particular syntax
is also not backwards-compatible; the compatible syntax is even more 
clumsy); see my *detailed* follow-up.
 
-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | <http://PointedEars.de/es-matrix>
<https://github.com/PointedEars> | <http://PointedEars.de/wsvn/>
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Thread

check for obj nested prop Andrew Poulos <ap_prog@hotmail.com> - 2020-05-08 15:37 +1000
  Re: check for obj nested prop Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-05-08 10:52 +0100
    Re: check for obj nested prop Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-09 00:26 +0200
      Re: check for obj nested prop Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-05-09 03:09 +0100
        Re: check for obj nested prop Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-12 09:28 +0200
          Re: check for obj nested prop Julio Di Egidio <julio@diegidio.name> - 2020-05-12 04:01 -0700
    Exception handling (was: check for obj nested prop) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-09 03:46 +0200
  Re: check for obj nested prop JJ <jj4public@vfemail.net> - 2020-05-08 17:18 +0700
  Re: check for obj nested prop Julio Di Egidio <julio@diegidio.name> - 2020-05-08 03:53 -0700
  Re: check for obj nested prop James Kirk <noneya.invalid@gmail.com> - 2020-05-08 11:00 -0400
  Re: check for obj nested prop Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-09 00:19 +0200
    Re: check for obj nested prop Julio Di Egidio <julio@diegidio.name> - 2020-05-12 04:04 -0700
      Re: check for obj nested prop luserdroog <luser.droog@gmail.com> - 2020-05-12 07:59 -0700
  Re: check for obj nested prop "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-05-12 14:17 -0700
    Re: check for obj nested prop Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-13 02:46 +0200
    Re: check for obj nested prop Andrew Poulos <ap_prog@hotmail.com> - 2020-05-13 13:08 +1000
      Re: check for obj nested prop "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-05-13 12:30 -0700

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