Re: Is polyfilling future web APIs a good idea?

On Sun, Aug 2, 2015 at 9:39 PM, Glen Huang <> wrote:
> I'm pretty obsessed with all kinds of web specs, and invest heavily in tools based on future specs. I was discussing with Tab the other day about whether he thinks using a css preprocessor that desugars future css is a good idea. His answer was surprisingly (at least to me) negative, and recommended sass. His arguments were that
> 1. the gramma is in flux and can change
> 2. css might never offer some constructs used in sass, at least with very low priority.
> I think these are good points, and it reduced my enthusiasm for future spec based css preprocessors. But this got me thinking about polyfills for future web APIs. Are they equally not recommended? Likewise, the APIs might change, and for DOM operations we should rely on React because the native DOM might never offer such declarative APIs, at least with very low priority. Do polyfills like WebReflection's DOM4 look promising? For new projects, should I stick with polyfills that only offers compatibilities for older browser, and for future spec features, only use libraries that offer similar features but invent their own APIs, or should I track future specs and use these "unstable" polyfills?
> I'm torn on this subject. Would like to be enlightened.

TL;DR: Yes, I think they are good - really good actually, with some
best practices.

CSS is a slightly different beast at the moment because it is not
(yet) extensible, but let's pretend for a moment that it is so that a
uniform answer works ok...

This was why I and others advocated defining the idea of/using the
term "prollyfill" as opposed to a polyfill.  With a polyfill you are
filling in gaps and cracks in browser support for an established
standard, with a prollyfill you might be charting some new waters.  In
a sense, you're taking a guess.  If history is any indicator then the
chances that it will ultimately ship that way without change is very
small until it really ships in two interoperable browsers that way.
There's more to it than slight semantics too I think:  Polyfill was
originally defined as above and now for many developers the
expectation is that this is what it's doing.  In other words, it's
just providing a fill for something which will ultimately be native,
therefore won't change.  Except, as we are discussing, this might not
be so.  Personally, I think this matters in a big way because so much
depends on people understanding things:  If users had understood and
respected vendor-prefixed CSS for use as intended, for example, they
wouldn't have been much of a problem -- but they were.  Users didn't
understand that and things shipped natively, so vendors had to adjust
- things got messy.

Debates about this took up a lot of email space in early extensible
web cg lists - my own take remains unchanged, mileage may vary:

It is my opinion that when possible, we should 'prefix' prollyfilled
APIs - this could be something as simple as an underscore in DOM APIs
or a "--property" in CSS, etc.  Hopefully this makes it obvious that
it is not native and is subject to change, but that isn't the reason
to do it.  The reason to do it is the one above:  it *may* actually
change so you shouldn't mislead people to think otherwise - it
potentially affects a lot.  For example, if something gets very
popular masquerading as native but no one will actually implement
natively it without changes - they are stuck having to deal with
shitty compromises in standards to keep the web from breaking.  Also,
what happens when devs "sell" a standard with the promise that it's
going to be native and then we rip that rug out from underneath them.

For me then, following a nice pattern where authors opt in and provide
whether or not to prefix is ideal.  Since authors opt in, just like
they do with a library and it can work in all browsers, it can
version, and it's way better than vendor prefixes on native.  Yes,
your code won't "automatically" run faster if it is implemented
natively- but depending on how far along the track you are, it might
be very long odds that it will ship just like that.  If you get very
lucky, your last version of "prollyfill" becomes "polyfill" and if a
site wants to use the native, they can tweak a single arg and it's off
to the races.

Realistically, I think that prollyfills are probably the only way to
strike the right balance of incentives and disincentives that allow
the standards community to do good things, create a good feedback loop
that developers can actually be involved in and measure something
experimental before we ship it.

Brian Kardell :: @briankardell ::

Received on Monday, 3 August 2015 02:17:18 UTC