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Re: HTML5 embed element event

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Michael Haufe (TNO) wrote:

> On Thursday, May 21, 2020 at 11:53:31 AM UTC-5, Thomas 'PointedEars' Lahn
> wrote:
>> I forgot about Set.  I do not know what you mean by “featureNames”,
> 
> Sorry, that was a copy/paste issue from other code I'm working on which
> focuses on classes instead of objects. A 'feature' in the context of a
> class is a property, a method, or an accessor. This terminology is seen in
> compiler work and in some literature such as:
> 
> "Feature-Oriented Programming with Object Algebras"
> <https://www.cs.utexas.edu/~wcook/Drafts/2012/FOPwOA.pdf>

As I mentioned recently, I have been using the term “feature” in my code for 
ages[tm] :)
 
>> or why you would pass a reference to a two-element Array.

I see now that actually you are NOT doing that.  The new meaning of “...” in 
ECMAScript just has not entered my subconscious yet.

For the interested, unaware reader: “...” is not an omission (Perls are 
warned now), but works *like* an *operator* now (ECMAScript 2015+), such 
that

  [...['foo', 'bar'], ...['baz', 'bla']]

is now equivalent to

  ['foo', 'bar', 'baz', 'bla']

which is most useful if ['foo', 'bar'] and ['baz', 'bla'] are return values.  
Array.prototype.concat(), Array.prototype.push(), and simple uses of 
Function.prototype.call() and Function.prototype.apply() are thus rendered 
unnecessary.

  a.concat('foo', 'bar')       → [...a, ...['foo', 'bar']]
  a.push('foo', 'bar')         → a = [...a, ...['foo', 'bar']]
  o.f.call(o, 'foo', 'bar')    → o.f(...['foo', 'bar'])
  o.f.apply(o, ['foo', 'bar']) → o.f(...['foo', 'bar'])

Which means we can also finally write something like

  var input = '2020-05-21';
  new Date(...input.split('-').map((comp, i) => (i == 1 ? comp - 1 : comp)))

without a workaround.
 
> The constructor of Set accepts an iterable so you can do:
> 
> new Set([1,2,3])
> 
> Therefore in a single expression in declarative fashion we can define a
> set which contains all of the current property names, and all of the
> ancestor property names. To iterate is human, to recurse is divine.

I see.  Nice line :)

> Using the Set approach:
> 
> ```
> let propertyNames = obj =>
>   obj == null ? new Set() :
>     new Set([
>       ...Object.getOwnPropertyNames(obj),
>       ...featureNames(Object.getPrototypeOf(obj))

That would be ...propertyNames(…) here, I suppose.

>     ])
> 
> var el = $0;
> 
> [...propertyNames(el)]

IOW, now for simple cases .forEach(…) is rendered unnecessary, too? :-o

>   .filter(name => name.startsWith('on'))
                         ^^^^^^^^^^
Another "new" feature that had not entered my subconscious yet.

>   .forEach(name => el[name] = ev => console.log(ev));

For me, a readable code style requires at least braces around both function 
bodies here, as they are *statements*, not expressions.  (If they were more 
complex expressions, I would put them in parentheses instead; see above.)

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | <http://PointedEars.de/es-matrix>
<https://github.com/PointedEars> | <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | Please do not cc me./Bitte keine Kopien per E-Mail. 

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Thread

HTML5 embed element event Andrew Poulos <ap_prog@hotmail.com> - 2020-05-19 16:39 +1000
  Re: HTML5 embed element event "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2020-05-19 17:29 +0200
    Re: HTML5 embed element event Andrew Poulos <ap_prog@hotmail.com> - 2020-05-20 07:45 +1000
      Re: HTML5 embed element event "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2020-05-20 00:21 +0200
        Re: HTML5 embed element event rcpj@panix.com (Pierre Jelenc) - 2020-05-20 01:09 +0000
          Re: HTML5 embed element event Andrew Poulos <ap_prog@hotmail.com> - 2020-05-20 18:36 +1000
          Re: HTML5 embed element event "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2020-05-20 12:36 +0200
  Re: HTML5 embed element event "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-05-19 17:21 -0700
    Re: HTML5 embed element event Andrew Poulos <ap_prog@hotmail.com> - 2020-05-20 18:43 +1000
  Re: HTML5 embed element event Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-21 17:15 +0200
    Re: HTML5 embed element event "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-05-21 08:55 -0700
      Re: HTML5 embed element event "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-05-21 08:57 -0700
        Re: HTML5 embed element event Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-21 18:53 +0200
          Re: HTML5 embed element event "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-05-21 11:00 -0700
            Re: HTML5 embed element event Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-21 21:50 +0200
              Re: HTML5 embed element event Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-21 22:03 +0200
              Re: HTML5 embed element event "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-05-21 15:25 -0700
                Re: HTML5 embed element event Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-05-23 03:06 +0200

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