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From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups: comp.lang.javascript
Subject: Re: Object prop missing?
Date: Thu, 13 Jun 2019 17:30:09 +0200
Organization: PointedEars Software (PES)
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Xref: csiph.com comp.lang.javascript:36905

Andrew Poulos wrote:

> […] but what I can't understand is with this:
> 
>    console.log(options[1]);   // 1.
>    console.log(options[1].h); // 2.
> 
> why 1. shows a value for h yet 2. (which immediately follows 1.) says h
> is undefined.

Very simple: You have not added the property to the object referred to by 
“options[1]”, you have added it and removed it later, or you have set it to 
“undefined”.  “JJ”’s argument is sound as well.

For example, one can create an object that cannot be augmented with 
properties:

  var obj = Object.freeze({});

  /* TypeError exception only in strict mode */
  obj.h = 42;
  
  /* undefined */
  console.log(obj.h);

This behavior actually applies to primitive strings since ECMAScript Ed. 5.
[If one wishes to call custom methods on string values, one must augment the 
String prototype, or use .call() or .apply() instead.]

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PointedEars
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