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Re: [FileAPI] File.slice spec bug

From: Jian Li <jianli@chromium.org>
Date: Tue, 12 Apr 2011 13:08:58 -0700
Message-ID: <BANLkTimj5+BW=mMJLCtN2oqA8+K2PRdGOQ@mail.gmail.com>
To: "arun@mozilla.com" <arun@mozilla.com>, Darin Fisher <darin@chromium.org>, Maciej Stachowiak <mjs@apple.com>
Cc: Jonas Sicking <jonas@sicking.cc>, Web Applications Working Group WG <public-webapps@w3.org>, Eric Uhrhane <ericu@google.com>, "dimich@chromium.org" <dimich@chromium.org>
The biggest concern is that this is a breaking change and quite a few web
applications have already been using it. As far as I know, File.slice(start,
length) has been supported as early as Chrome 6 and Safari 5. Also Firefox 3
is supporting it. How do we communicate with web developers about this
breaking change if we decide to make the change?


On Tue, Apr 12, 2011 at 11:34 AM, Arun Ranganathan <arun@mozilla.com> wrote:

> On 4/12/11 2:24 PM, Jonas Sicking wrote:
>> Hi All,
>> It was recently (yesterday) pointed out to me that we let a bad
>> spec-bug slip through for File.slice. It doesn't match the argument
>> semantics of Array.slice which can be very confusing for developers.
>> In Array.slice the second argument is the index of the last item to be
>> included in the returned slice.
>> In File.slice the second argument is the number of bytes included in
>> the returned slices.
>> In other words, it's Array.slice(start, end), but File.slice(start,
>> length).
>> Additionally, in Array.slice the second argument is optional.
>> File.slice is currently shipped by Chrome and Firefox 4. I would be
>> fine with fixing this in Firefox 4.0.1, however that only makes sense
>> if the chrome folks are fine with fixing it in their implementation.
>> So consider this an official request, would chrome be ok with changing
>> the spec here?
>> / Jonas
> I'm bummed that we collectively let this slip through the cracks, and
> personally think it's early enough to fix it.  But we should also decide how
> closely to match Array.slice.  Should we allow code of the sort
> file.slice(-80)?
> Code of that sort is allowed with Array.slice.
> MDC has good developer docs about what's in Firefox for Array.slice:
> https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/slice
> Developers may have already discovered file.slice (e.g. see
> http://hacks.mozilla.org/2011/04/resumeupload/), so fixing this will
> involve some messaging.
> -- A*
Received on Tuesday, 12 April 2011 20:09:44 UTC

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