oliver at apple.com
Mon Jun 15 11:55:37 PDT 2009
> - Pre-Compiled: By bundling known JS Libraries with the browser, the
> browser could store a more efficient representation of the file.
> For instance pre-compiled into Bytecode or something else browser
I think something needs to be clarified wrt to compile times and the
like. In the WebKit project we do a large amount of performance
analysis and except in the most trivial of cases compile time just
doesn't show up as being remotely significant in any profiles.
Additionally the way JS works, certain forms of static analysis result
in behaviour that cannot reasonably be cached. Finally the optimised
V8 and (i *think*) TraceMonkey is not amenable to caching, even within
a single browser session, so for modern engines i do not believe
caching bytecode or native is really reasonable -- i suspect the logic
required to make this safe would not be significantly cheaper than
just compiling anyway.
> - Less HTTP Requests / Cache Checks: If a library is in the
> repository no request is needed. Cache checks don't need to be
> performed. Also, for the 100 sites you visit that all send you the
> equivalent jquery.js you now would send 0 requests. I think this
> would be enticing to mobile browsers which would benefit from this
> Space vs. Time tradeoff.
I believe http can specify how long you should wait before validating
the cached copy of a resource so i'm not know if this is a real win,
but i'm not a networking person so am not entirely sure of this :D
> - Standardizing Identifier For Libraries: Providing a common
> identifier for libraries would be open for discussion. The best
> idea I've had would be to provide the SHA1 Hash of the Desired
> identifier for the same source file across browsers that support the
> feature. This would be useful for developers as well. A debug tool
> can indicate to a developer that the script they are using is
> available in the Browser Repository with a certain identifier.
This isn't a pro -- it's additional work for the standards body
> - May Not Grow Fast Enough: If JS Libraries change too quickly the
> repository won't get used enough.
> - May Not Scale: Are there too many JS Libraries, versions, etc
> making this unrealistic? Would storage become too large?
- Adds significant spec complexity
- Adds developer complexity, imagine a developer modifies their
servers copy of a given script but forgets to update the references to
the script, now they get inconsistent behaviour between browsers that
support this feature and browsers that don't.
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