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From: "Christoph M. Becker" <cmbecker69@arcor.de>
Newsgroups: comp.lang.javascript
Subject: Re: Why does (a,b,c) return only c?
Date: Mon, 25 May 2015 14:57:50 +0200
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Evertjan. wrote:

> Steven D'Aprano <steve@pearwood.info> wrote on 25 mei 2015 in 
> comp.lang.javascript:
> 
>> Consider:
>>
>> js> var x = (1,2,3);
>> js> x
>> 3

Because ECMAScript implementations don't have a tuple type like Python has.

> So it seems just a set of statements executed in line,
> the result value of the last one returned.

See <http://www.ecma-international.org/ecma-262/5.1/#sec-11.14> for details.

> However this errors:
> 
> (var i=4,++i,i=i*10,a=7,-3,i++);
> 
> Why?

A variable statement is not allowed in an expression, see
<http://www.ecma-international.org/ecma-262/5.1/#sec-11.1>.

-- 
Christoph M. Becker