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Groups > comp.lang.javascript > #28029
| From | Martin Honnen <mahotrash@yahoo.de> |
|---|---|
| Newsgroups | comp.lang.javascript |
| Subject | Re: Calling constructor function with or without new |
| Date | 2015-06-07 19:46 +0200 |
| Organization | Liberty Development |
| Message-ID | <ml2021$1at3$1@adenine.netfront.net> (permalink) |
| References | <55745048$0$13014$c3e8da3$5496439d@news.astraweb.com> |
Steven D'Aprano wrote:
> I'm using Rhino. What's the difference between calling a constructor with or
> without new?
>
> js> var x = Number("123");
> js> print(x);
> 123
> js> typeof x;
> number
As you use Rhino which I think did never get updated to implement
ECMAScript 5 you might want to download
http://www.ecma-international.org/publications/files/ECMA-ST-ARCH/ECMA-262,%203rd%20edition,%20December%201999.pdf
and read section "15.7.1 The Number Constructor Called as a Function"
which says "When Number is called as a function rather than as a
constructor, it performs a type conversion." and defines
Number ( [ value ] )
as
Returns a number value (not a Number object) computed by
ToNumber(value) if value was supplied,
else returns +0.
The type conversions "ToNumber" performs depending on the type of the
value are defined in section "9.3" of that PDF.
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Calling constructor function with or without new Steven D'Aprano <steve@pearwood.info> - 2015-06-08 00:08 +1000
Re: Calling constructor function with or without new Martin Honnen <mahotrash@yahoo.de> - 2015-06-07 19:46 +0200
Re: Calling constructor function with or without new Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-06-07 21:50 -0300
Re: Calling constructor function with or without new Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-06-09 15:05 +0200
Re: Calling constructor function with or without new Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-06-09 12:45 -0300
Re: Calling constructor function with or without new Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-06-09 18:32 +0200
Re: Calling constructor function with or without new Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-06-09 14:51 -0300
Re: Calling constructor function with or without new Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-06-09 22:39 +0200
Re: Calling constructor function with or without new Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-06-09 19:36 -0300
Re: Calling constructor function with or without new Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-06-10 18:14 +0200
Re: Calling constructor function with or without new Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-06-10 14:13 -0300
Re: Calling constructor function with or without new Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-06-10 19:34 +0200
Re: Calling constructor function with or without new Joao Rodrigues <groups_jr-1@yahoo.com.br> - 2015-06-10 14:57 -0300
Re: Calling constructor function with or without new Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-06-10 20:00 +0200
Re: Calling constructor function with or without new Dr J R Stockton <reply1500@merlyn.demon.co.uk.invalid> - 2015-06-11 21:44 +0100
Re: Calling constructor function with or without new Hans-Georg Michna <hans-georgNoEmailPlease@michna.com> - 2015-06-11 10:36 +0200
Re: Calling constructor function with or without new Scott Sauyet <scott.sauyet@gmail.com> - 2015-06-11 06:16 -0700
Re: Calling constructor function with or without new "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2015-06-11 20:40 -0700
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