[whatwg] Fwd: Don't throw for HTMLInputElement.files

Garrett Smith dhtmlkitchen at gmail.com
Tue Jun 15 16:01:59 PDT 2010

Jonas suggested I fwd these comments to the list.

---------- Forwarded message ----------
From: Garrett Smith <dhtmlkitchen at gmail.com>
Date: Tue, 15 Jun 2010 15:04:16 -0700
Subject: Re: [whatwg] Don't throw for HTMLInputElement.files
To: Jonas Sicking <jonas at sicking.cc>

On 6/15/10, Jonas Sicking <jonas at sicking.cc> wrote:
> Hi All,
> Currently HTMLInputElement.files throws if accessed when type !=
> "file". I think it would be better to return null or an empty list. We
> generally try to avoid throwing in general, and in particular things
> like HTMLInputElement.checked doesn't throw even if the value doesn't
> apply. So for consistency I don't think HTMLInputElement.files should
> throw either.

The calling code can perform a check - if(x.type == "file") -. I can't
see a good reason for not having x.files be designed to return
`undefined`. Besides, throwin an error there is totally inconsistent
with other state-specific properties (like `valueAsNumber` or
`valueAsDate` etc). On those, both of those are needless complexity
anyway; +inp.value is a common-use alternative to valueAsNumber and
valueAsDate can be gotten by using the Date constructor, which,
although buggy in Firefox, is specified in ES5 to parse a superset of
the ISO8601 formats in HTML5.

> Another reason not to throw is that people every so often enumerate
> all the IDL attributes of element using |for each| constructs in

The for-in loop. |for each| is a spidermonkey syntax extension. It is
not widely implemented and nobody uses it.


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