Comments on: Caching scripts in HTML5 Database

By: ujuxiun

ujuxiun — Tue, 24 Feb 2009 06:45:31 +0000

this general technique can speed page loading by 30% or better esp for mobile devices. like 343max mentioned the If-Modified-Since/Last-Modified headers can be used in your xmlhttprequest (set/getResponseHeader) if/when you have them available instead of tinkering with versioning. that way you can delay or ignore 304/not-modified responses keeping persistent assets current in the background.

By: sujith84

sujith84 — Sat, 21 Feb 2009 04:48:29 +0000

great tip. although i will never by using it, it is still a very good method.

By: 3n

3n — Fri, 20 Feb 2009 18:50:44 +0000

343max – that’s pretty slick, well done. I didn’t have access to the mod dates since I’m doing it entirely in JS (no php 4 me), so I had to use version numbers :(

By: 3n

3n — Fri, 20 Feb 2009 18:48:22 +0000

The reason for using this over expire headers is that iPhone currently wont cache any file over 25K (e.g. most JS libraries). Even if it were to cache large files, it has pretty aggressive cache clearing policies, including clearing the whole cache when it is hard reset.

The reason for using eval() over script tags is that I couldn’t figure out a way to sanitize the ” chars in the code properly in the amount of time I spent on this script. Without the sanitization, inserting the script’s code into script tags caused some nasty bugs. I still have a branch in my git repo that uses the script tags, though – if someone knows how to sanitize the code please message me on github.

I’m not sure why anyone would care about security issues in this case, but I guess that’s just all some people see..

By: karnius

karnius — Fri, 20 Feb 2009 18:40:30 +0000

Well the html spec say’s no one but the domain owner can change a html5 database as for security, I really like the idea anyway..

By: 343max

343max — Fri, 20 Feb 2009 15:30:50 +0000

I did something quite similar, but with Support for JS, CSS (with images).

Uses modification dates and not version numbers to make things easier to deploy.

Works in Webkit only (but on the iPhone)

http://github.com/343max/dbfs/tree/master

Real-life example: http://i.edween.net (works only in Webkit Browsers)

By: jeromeetienne

jeromeetienne — Fri, 20 Feb 2009 14:43:48 +0000

I did something similar with googe gear for symfony (php framework). you can find it at http://www.symfony-project.org/plugins/sfGoogleGearCachePlugin

By: KitSunde

KitSunde — Fri, 20 Feb 2009 13:14:31 +0000

Well http headers only works on a per-url basis while say this would work by allowing say a library to cache itself globally. Although I’m not sure that’s even reasonable considering the security implications of allowing unknown third party users too cache something for you.

I suppose this would also be a workaround if you are on a badly configured server who’s backend you’ve got no control over. Although its so easy to switch hosting these days, so I doubt that’s a real issue.

By: MorganRoderick

MorganRoderick — Fri, 20 Feb 2009 12:54:36 +0000

While it certainly is an interesting idea as a proof-of-concept, I fail to see the real-world scenarios, where this would be preferable to using cache expiration headers and versioning using url suffixes.

By: V1

V1 — Fri, 20 Feb 2009 12:35:52 +0000

Seems like a nice idea, but ill rather use expire headers..

instead of eval, why don’t you just create script tags, add the code as + text and append it to the head?