Re: Function Objects

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Message-ID	<1615243.oMNUckLgyt@PointedEars.de> (permalink)
From	Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To	Thomas 'PointedEars' Lahn <cljs@PointedEars.de>
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Date	Wed, 20 Jun 2012 15:43:24 +0200
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Subject	Re: Function Objects
Newsgroups	comp.lang.javascript
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Stefan Weiss wrote:

> The effect may be easier to understand if you use a simpler
> self-contained example without host objects:
> 
>     var dog = {
>         noise: "wow!",
>         bark: function () { alert(this.noise); }
>     };
> 
>     dog.bark();  // "wow!"
> 
>     var alias = dog.bark;
> 
>     alias();  // "undefined"
> 
> The last line yields "undefined" because |this| in the function body now
> refers to the global object, which has no "noise" property.

Evaluation of `this.noise' throws a TypeError exception in strict mode when 
alias() is called, because `this' would be `undefined' then, and `undefined' 
by definition has no properties.

The strict mode of ECMAScript (introduced in Edition 5 [1]) is particularly 
useful if you want to avoid accessing the global object, but it is neither 
correctly implemented in otherwise conforming implementations yet nor 
available in all implementations at all.  However, if you `"use strict";' 
mode, and test your code with a sufficiently conforming implementation (like 
Google V8 3.7.12.12 in Chrome 17.0.963.78¹), a lot of common programming 
mistakes can be avoided.

PointedEars
___________
¹ This feature and tests thereof are contained in the next version of the
  ECMAScript Support Matrix that I am preparing.

[1] <http://ecma-international.org/ecma-262/5.1/#sec-C>
-- 
When all you know is jQuery, every problem looks $(olvable).

Thread

Function Objects Gene Wirchenko <genew@ocis.net> - 2012-06-19 16:35 -0700
  Re: Function Objects Stefan Weiss <krewecherl@gmail.com> - 2012-06-20 02:09 +0200
    Re: Function Objects Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-06-20 15:43 +0200
    Re: Function Objects Stefan Weiss <krewecherl@gmail.com> - 2012-06-20 17:29 +0200

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