Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!feeder1.news.weretis.net!news.solani.org!.POSTED!not-for-mail From: Thomas 'PointedEars' Lahn Newsgroups: comp.lang.javascript Subject: Re: Difference between two arrays Date: Sun, 01 Jun 2014 16:53:09 +0200 Organization: PointedEars Software (PES) Lines: 31 Message-ID: <1877659.SCTd7HLFcV@PointedEars.de> References: <85360d2c-679b-4d2f-b2f6-4ef9b4c83bd5@googlegroups.com> <3666460.GdagG9gyNt@PointedEars.de> <2612098.u947hoiqVY@PointedEars.de> Reply-To: Thomas 'PointedEars' Lahn Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit X-Trace: solani.org 1401634391 10727 eJwNxkkBACAIBMBKcixoHEDoH0HnNRAjK1eDKQZzgZHT4F5C5JVcnpSzmyyWqPZPAREnsnk/HKcRUw== (1 Jun 2014 14:53:11 GMT) X-Complaints-To: abuse@news.solani.org NNTP-Posting-Date: Sun, 1 Jun 2014 14:53:11 +0000 (UTC) User-Agent: KNode/4.12.4 X-User-ID: eJwNyckNwDAMA7CVqviKx1HdaP8Rmh8BhiVyyjPSQyGoMq53ru0POAH2LZAQeKaPcUvW9ZEzVh2va/z4Mih/OjoVZg== Face: 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 X-Face: %i>XG-yXR'\"2P/C_aO%~;2o~?g0pPKmbOw^=NT`tprDEf++D.m7"}HW6.#=U:?2GGctkL,f89@H46O$ASoW&?s}.k+&. IOW, in order to have only a key-value relationship in an ECMAScript > implementation like JavaScript, you do not need an array (and chances are > you do not want to, because Array instances have and inherit more > properties that would interfere); you just need an object. In the > simplest case, an Object instance, created in conforming implementations > of ECMAScript 5.1 Edition thus: > > var obj = Object.create(null); > > Or equivalents of that (see jsx.object.getDataObject() in JSX:object.js); > the important thing here is that the prototype chain of the object is > empty so that in the best case it neither has nor inherits properties > whose names could interfere with "array" items. Otherwise you need to > implement the concept of associative array in a more elaborate way, ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > avoiding built-in properties through aliasing (see JSX:map.js for an > example). And, I forgot to emphasize, in general you need such a user-defined associative-array implementation to deal with "keys" that are not Strings. Because property names are primitive string values internally, and "keys" are converted to the String type. For example, without user-defined getters/setters, a[1] and a["1"] are equivalent expressions. -- PointedEars FAQ: | SVN: Twitter: @PointedEars2 | ES Matrix: Please do not Cc: me. / Bitte keine Kopien per E-Mail.