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Why Parse the User Agent?

jefftk.com

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Re: Why Parse the User Agent?

#41

Post by tracker1 »

sauere wrote: post #3
gkoberger wrote: post #2

The author dismisses feature detection as being "slow", but it's much less error prone: http://www.stucox.com/blog/using-webp-with-modernizr/ You can just cache the result in localStorage; you take a few-millisecond hit once. Here's how the feature detection is done: https://github.com/Modernizr/Modernizr/blob/924c7611c170ef2d... HOWEVER , in this case (webp), it's likely better to detect it on the server: https://gi…

> The only time you really should be looking at the User Agent is if you're trying to do something like show a "Download for (Chrome|Firefox|etc)" button. Amen.

I'm currently working on a site that uses react/flux with some use of media queries and size detection for rendering... effectively the phone and portrait tablet displays will be similar, and the desktop and large displays will also be similar... I'd prefer to be able to break this into two camps for the initial html sent to the browser (via server-side rendering) This way less is sent to the phone/tablet browsers to render initially... and less jarring change as other features load after initial display.

The only way to do this is browser sniffing.. although minimal.. for the most part if "phone" or "mobile" are in the browser I can send the lighter phone version... otherwise they initially get the desktop view. It isn't perfect, and to be honest, I'm doing more detection than just that.

There's also issues with where/when I can cash rendered output. And when/where I can cash certain results. For example the record id's for a given search will cache the first 10k id's so that paging becomes very fast, with the results limited to that set. Other queries will also be cached.

It really depends on what you are trying to do... growing from a few thousand users to millions takes some effort, planning, and thoughtfulness that isn't always the same.

The way I would design an app for a few hundred internal users isn't the same as for a public site, isn't the same for a very busy public site. You have to make trade offs or collapse.

Why should a phone user on a strained 3g connection get the content for a desktop browser.... By the same token, I HATE when I get a search result for a page on my phone, and that site redirects me to m.site.com/ (no path after /)... I don't just design/develop web based applications, I'm also a user...

Re: Why Parse the User Agent?

#42

Post by jed_watson »

calineczka wrote: post #7

I imagine that in the future with HTTP2 we could send the list of available browser features as HTTP headers such as Animated-WebP: Supported ? With HTTP1 the cost of sending long list of available features would be too big probably. But could HTTP2 solve this problem. If I recall correctly it only sends diffs of headers between subsequent requests in the same connection. Maybe that could be helpful for a class of pr…

I was just thinking a similar thing. If user agents have evolved to effectively become a way of saying "Our browser supports standards X" (where X is an awkward grouping based on which features vendors and browser versions originally supported the feature / standard), surely the ultimate solution is to provide a header enumerating support on a per-feature basis.

Obviously it would take a while for the standard to be adopted to the point where it was useful, but as a web developer I dream of a time when we receive a header that lists the supported features in the client (similar to the classnames modernizer adds to the document body, and probably eventually versioned) and no longer have to resort to either UA parsing OR javascript-based feature detection, both of which are hacks because this problem hasn't actually been solved properly at the standards level.

Re: Why Parse the User Agent?

#43

Post by takeda »

anon1385 wrote: post #40

I do find it slightly strange that saving a few bytes from the size of an image is suddenly of such pressing importance that we need to resort to all these hacks. JPEG2000 has been available in some browsers for years and years now, but I've yet to see any site selectively sending it to supporting browsers to save bandwidth, or anybody advocating for doing that. JPEG2000 first became available in browsers 10+ years a…

Also the appropriate way of declaring what browser supports should be done through the Accept http header.

Re: Why Parse the User Agent?

#44

Post by ronancremin »

jgraham wrote: post #10

Unfortunately, encouraging people to parse the UA header leads to them getting it wrong in a way that would be amusing if it wasn't so irritating. For example FirefoxOS has a UA string of the from User-Agent:Mozilla/5.0 Mobile Gecko/28 Firefox/32.0'. There's an example in bugzilla of a major site that, not only depends on the file details of that format, but will send the mobile version of the site if and only if the…

The trick is not to do it yourself, this is a complex enough problem that it's worth leaving to others to do if it really matters to you.

https://github.com/OpenDDRdotORG/OpenDDR-Resources http://deviceatlas.com

Re: Why Parse the User Agent?

#45

Post by csirac2 »

calineczka wrote: post #7

I imagine that in the future with HTTP2 we could send the list of available browser features as HTTP headers such as Animated-WebP: Supported ? With HTTP1 the cost of sending long list of available features would be too big probably. But could HTTP2 solve this problem. If I recall correctly it only sends diffs of headers between subsequent requests in the same connection. Maybe that could be helpful for a class of pr…

In this specific use-case wouldn't plain old content-negotiation/accept headers work?

Re: Why Parse the User Agent?

#46

Post by csirac2 »

jimktrains2 wrote: post #16

Isn't the problem more that the browser can't be given multiple sources and types and allow it to chose what it believes is best? User-Agent sniffing really does need to die. Part of me wonders what use UA headers serve beyond sniffing and analytics. EDIT: or the Accept (and content-type) header, but that's a next to worthless header anymore :-\

Why are accept headers next-to-worthless? I'm not heavily involved in front-end stuff these days but it's something I've relied on for years by now - admittedly not for image/media content, but still I'm curious.

Re: Why Parse the User Agent?

#47

Post by idlewan »

anon1385 wrote: post #40

I do find it slightly strange that saving a few bytes from the size of an image is suddenly of such pressing importance that we need to resort to all these hacks. JPEG2000 has been available in some browsers for years and years now, but I've yet to see any site selectively sending it to supporting browsers to save bandwidth, or anybody advocating for doing that. JPEG2000 first became available in browsers 10+ years a…

> JPEG2000 first became available in browsers 10+ years ago

Apart from Safari (https://en.wikipedia.org/wiki/JPEG_2000#Application_support), I'm not sure it's supported at all.

Re: Why Parse the User Agent?

#48

Post by drdaeman »

markbnj wrote: post #25
jgraham wrote: post #10

Unfortunately, encouraging people to parse the UA header leads to them getting it wrong in a way that would be amusing if it wasn't so irritating. For example FirefoxOS has a UA string of the from User-Agent:Mozilla/5.0 Mobile Gecko/28 Firefox/32.0'. There's an example in bugzilla of a major site that, not only depends on the file details of that format, but will send the mobile version of the site if and only if the…

There's a whole class of old ASP sites that break if you take "like Gecko" out of the UA. It would be funny if it hadn't made me cry so often.

Why not just break them?

Re: Why Parse the User Agent?

#49

Post by clarry »

mitchty wrote: post #37
jimktrains2 wrote: post #12

Earlier quoted context omitted.

What image formats are you hitting that Preview (I'm guessing you're on a Mac?) won't open? BTW: gthumb opens it A-OK. So, maybe the issue isn't the openness of the format, but the openness of your platform?

Openness of your platform? God could we get any more passive aggressive with this open source bullshit? Honestly this kind of crap is like doing grade school all over again. Grow up already, does windows support webm/webp natively? Nope, needs plugins. Webp is in a lot of the same boat as webm legally. It may be "open", whatever the fuck that means anymore, but that doesn't make it patent free or not needing of any l…

> Even webm infringed on H264 patents as of 2013

Where's your proof?

Re: Why Parse the User Agent?

#50

Post by vertex-four »

drdaeman wrote: post #48
markbnj wrote: post #25

Earlier quoted context omitted.

There's a whole class of old ASP sites that break if you take "like Gecko" out of the UA. It would be funny if it hadn't made me cry so often.

Why not just break them?

Because then people use a competing browser that doesn't break the sites they use.
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