Le 25/05/2014 14:04, Michael Heuberger a écrit :
Bonjour David

On 25/05/14 23:33, David Bruant wrote:
Hi Michael,

Le 25/05/2014 07:10, Michael Heuberger a écrit :
Look at Angular, their templates reside on the client side. For
production, a grunt task can compress all files into one single, huge JS
file that is served to the client, then for any subsequent pages no more
resources are loaded from the server. It is a widely used practice.
Look at React.js, it allows to render templates on the server side and
it's been a selling point for some people (it allows to generate the
same page whether you are on the client or server-side. It helps for
SEO sometimes).
Yeah, each framework has it's own way - nevertheless, Angular is very
popular these days.
"these days" is not an argument. We're discussing an addition to the web platform and as we know, things are hard to remove after they've been added [1]. Frameworks come and go, the platform stays (so far at least)

Serving different content based on different URLs (and status)
actually does make a lot of sense when you want your user to see the
proper content within the first HTTP round-trip (which saves
bandwidth). If you always serve generic content and figure it all out
on the client side, then either you always need a second request to
get the specific content or you're always sending useless data during
the first generic response which is also wasted bandwidth.
Good point. From that point of view I agree but you forgot one thing:
The user experience. We want mobile apps to be very responsive below
Agreed (on UX and responsive applications)

Hence the two requests. The first one ensures the SPA to be
loaded and the UI to be initialized. You'll see some animation, a text
saying "Fetching data" whatever. Then the second request retrieves the
specific content.
What I'm proposing is that all the relevant content is served within
the *first* request. The URL is used by the client to express to the
server (with arbitrary granularity, it depends on your app, obviously)
what the user wants.
What I'm proposing is not two requests to get the proper content, but
only one. The user doesn't even have to wait with a useless "Fetching
data" screen; the useful content is just there within the first
request (hence server-side rendering with React or Moustache or else
being useful).
Yeah of course I could do that too. It is psychologically proven that
the subjective waiting time is shorter when you see something as soon as
Yes and what I'm suggesting is providing actual content as soon as possible. The whole idea of the "critical rendering path" is exactly about engineering your webpage so useful content is provided to the user as soon as possible (which is as soon as you're currently capable of showing a "Fetching data" screen).

If you're being serious about bandwidth and UX (including percieved performance), it's exactly what you should be doing, I believe.

Furthermore you can convert a whole single page app into an iPhone app
with PhoneGap. All the HTML resides in the app, not on the server.
That's a very different approach and a good reason why JavaScript has
the right to know if the HTTP request resulted into a 200 or a 404.
If all the HTML resides in the app, not on the server, then it wasn't
served via HTTP, so there is no 200 or 404 to inform about (since no
HTTP request occured).
Ah, well spotted. PhoneGap comes with two options:
a) You can choose to reside the whole HTML in the app or
b) have it served from the server during the first HTTP request.

Option a) saved bandwidth but you cannot update pages easily (option b).

Option a) wouldn't need to know if it's a 200 or 404, you are right.
Still, option b) needs to know the status code.
Option b) sounds like a bookmark, so it's a regular web page, so the
arguments against stand (?)
Yes like a bookmark. And that's a case where it would be great to read
the HTTP status code from JavaScript.
Continuing the argument from above, the bookmark is to a specific URL and so, for the sake of bandwidth and UX, you should be serving different content for different URLs, so you don't need the HTTP status code

Let me ask you another question:
Is there a good reason NOT to give JavaScript a chance to find out the
HTTP status code of the current page?
By that argument, an absurd amount of features should go in ;-)
Really? How many "absurd amount of features" do you guys get every day?
http://lists.whatwg.org/pipermail/whatwg-whatwg.org/2014-May/296902.html ? This suggestion is mostly harmless, but doesn't really add value in my opinion. I am less active on standards mailing-lists these days, so I cannot count, but others will know better.

 From a more "social" standpoint, it bothers me, because it means
people serve the exact same content for all URLs, which defeats the
very purpose of why URLs were invented in the first place.
Ummm, I am not sure if I can follow you. What do you mean with "people
serve the exact same content for all URLs"?
I meant "people write servers which serve the exact same content for all URLs".

It is absolutely normal that URLs change or become invalid, hence the
need for status codes. You know ...

You want to serve the same content regardless of the URL and then have
client-side code read the URL and change the page state based on the
URL. We already have a standardized way to express a part of the URL
that is only interpreted on the client side which is the hash
(everything after '#'). Format your URLs using # if that's your
My single page app works without the # part and uses absolutely
normal-looking URLs to make it easier for search engine to spider it.
Then why serving the exact content on every URL?

Also, given that you always serve the same content and only figure
things out on the client side, why does your server sometimes answer
404? Deciding whether the URL is erroneous should occur on the
client-side, no?
Anyway, so far, what you're asking for seems like it's only
encouraging misusage of existing technologies.
Okay, I have a huge sign language video library here for Deaf people.
Anyone can add / edit / delete stuff. Each video has an unique URL. When
I load a page of a deleted video, a 404 is returned with the whole SPA
code and additional stuff is rendered to deal with 404s in a nice way to
improve usability. Here you have a real-world example and it is not a
misusage of technologies.
I still see a misuse of URLs.
Why aren't you serving a different page for 404s? The perceived performance would be better for your users.

Even if there is a way to read the HTTP status code, the user has to wait for:
1) the HTML + the SPA code to be downloaded
2) the SPA to read the HTTP status code, build the error page
3) display the error page

If you serve a different content on 404, the user has to wait:
1) the HTML to be downloaded (which naturally displays the page)
2) (then, you can improve the experience with the JS code which downloads while the user is reading that they're on the wrong page)

PS: I wonder how the WhatWG procedure looks like? Are you all working
for the WhatWG and deciding which features to implement?
Others will correct the specifics, but the WHATWG is an informal (?) group of browser vendors. This mailing list is open to anyone (and obviously web browser engineers participate to this list). In the end, browser vendors make the call of what they want to implement (regardless of any sort "standardization" process as EME showed again, thanks Microsoft and Google!). Browser vendors have a lot on their plates, so they'll implement something only if they see strong support or a strong need. I believe that's why you've been sent to this mailing-list by Mozilla engineers ;-)

I'm personally not attached to any browser vendor (but contribute to MDN and a couple of Mozilla projects occasionally). I don't make any decision. I'm a web developer, carrying a web developer point of view (which browser vendors make what they want of but is sometimes helpful for them to figure out what to implement and what not).
Basically, I'm just making conversation :-)


[1] http://glazkov.com/2014/04/24/going-forward-is-leaving-past-behind/

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