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Message-ID: <15066019.Edmlg4qf5b@PointedEars.de>
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To: Thomas 'PointedEars' Lahn <usenet@PointedEars.de>
Organization: PointedEars Software (PES)
Date: Mon, 20 May 2013 14:23:47 +0200
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Subject: Re: jslint and typeof
Newsgroups: comp.lang.javascript
References: <kr2dnRlKLtGEaQTMnZ2dnUVZ_g6dnZ2d@westnet.com.au> <kncubd$i57$1@dont-email.me> <m2r4h16g1i.fsf@nntp.bednarz.nl>
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Eric Bednarz wrote:

> "Jukka K. Korpela" <jkorpela@cs.tut.fi> writes:
>> the test
>>
>> typeof options.actor !== "undefined"
>>
>> is unnecessary complicated, since you can use
>>
>> options.action !== undefined
> 
> This, however, is unnecessarily brittle since the undefined property of
> the global object is writable in ES < 5.

ACK.  And in earlier implementations there was no “undefined” property, 
causing this to throw (the equivalent of) a ReferenceError.

> It is also overly verbose.

In what way?
 
> options.action !== void 0;

I would call *that* overly verbose.  For backwards compatibility, I have 
occasionally declared

  var undefined;

However, nowadays the “!==” and “===” operators and the “undefined” property 
of the Global Object can generally be considered safe language features.  
Only a caveat with the property value and host objects must remain for the 
time being.

-- 
PointedEars

Twitter: @PointedEars2
Please do not Cc: me. / Bitte keine Kopien per E-Mail.