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[WebIDL][ES6] Include optional arguments in "length"

From: Simon Pieters <simonp@opera.com>
Date: Wed, 17 Oct 2012 09:49:51 +0200
To: "public-script-coord@w3.org" <public-script-coord@w3.org>
Message-ID: <op.wmbb1dk0idj3kv@simons-macbook-pro.local>
Hi,

ES6 and WebIDL do not include optional arguments in the "length" property.  
It would be more useful for feature testing DOM stuff if they were. Gecko  
currently includes them for DOM stuff, but there's a bug  
https://bugzilla.mozilla.org/show_bug.cgi?id=793151 about changing it to  
match current WebIDL. IE/Opera/WebKit seem to always use 0 for DOM stuff.  
WebIDL is apparently aligned with ES6: "The length property of a function  
should be updated to not include optional parameters."  
http://wiki.ecmascript.org/doku.php?id=harmony:parameter_default_values

Always using 0 is quite useless for feature testing, but not including  
optional arguments is also useless since you can't tell if the UA  
implements the optional argument or not. What was the rationale for not  
including optional arguments in length in ES6? Can we change both ES6 and  
WebIDL to include them?

-- 
Simon Pieters
Opera Software
Received on Wednesday, 17 October 2012 07:50:20 UTC

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