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From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups: comp.lang.javascript
Subject: Re: let syntax
Date: Tue, 16 Jun 2020 21:23:31 +0200
Organization: PointedEars Software (PES)
Lines: 42
Message-ID: <7793047.T7Z3S40VBb@PointedEars.de>
References: <Gt-dnYgvE8ieWHvDnZ2dnUU7-QnNnZ2d@westnet.com.au> <20200614212651.513dc927@james.kirk.invalid> <sa2dndANOaaDd3vDnZ2dnUU7-IfNnZ2d@westnet.com.au>
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Xref: csiph.com comp.lang.javascript:38469

Andrew Poulos wrote:

> On 15/06/2020 11:26 am, James Kirk wrote:
>> Andrew Poulos <ap_prog@hotmail.com> wrote:
>>> function move(e) {
>>>    let { target:el } = e;
>> 
>>>    if (el.nextElementSibling){
>>>      el.parentNode.appendChild(el);
>>>    }
>>> }
>>> […]
>> 
>>> I don't understand how the first line in "move" works. It seems that
>>>    let { target:el } = e;
>>> is equivalent to
>>>    let el = e.target;
>> 
>>> but how?
>> 
>> Destructuring assignment
>> 
>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment
> 
> Cool, a whole new area I knew nothing about!
> 
> In this case, why would choose one rather than the other?

DRY.  If you wanted to extract other properties, you just have to expand the 
destructuring assignment instead of writing one more assignment and 
duplicating the object reference on the right-hand side of the “=”.

Personally I find this particular syntax more confusing than helpful because 
what is being assigned *to* is now unexpectedly on the *right*-hand side of 
what can reasonably construed to be an assignment (“…: …”).

Compare: <https://github.com/airbnb/javascript#destructuring>

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