How do I get keys from an associative array?
in [JavaScript]
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From: laredotornado on 20 Feb 2010 20:31 Hi, Given an associative array, how do I get an array of the keys of that associative array? Thanks, - Dave
From: David Mark on 20 Feb 2010 21:01 laredotornado wrote: > Hi, > > Given an associative array, how do I get an array of the keys of that > associative array? > There's no such thing as an associative array in JS. If you mean an Object object, use a for-in loop to populate an array. And make sure you filter the loop with either hasOwnProperty or a similar wrapper (Google "for-in intrigue").
From: Thomas 'PointedEars' Lahn on 20 Feb 2010 21:37 laredotornado wrote: > Given an associative array, how do I get an array of the keys of that > associative array? Mu. <http://jibbering.com/faq/#posting> PointedEars -- Prototype.js was written by people who don't know javascript for people who don't know javascript. People who don't know javascript are not the best source of advice on designing systems that use javascript. -- Richard Cornford, cljs, <f806at$ail$1$8300dec7(a)news.demon.co.uk>
From: Lasse Reichstein Nielsen on 20 Feb 2010 22:27 laredotornado <laredotornado(a)zipmail.com> writes: > Given an associative array, how do I get an array of the keys of that > associative array? If arr is your associative array (i.e., an object) In ECMAScript 5: var keys = Object.keys(object) In ECMAScript 3: var keys = []; for (var key in arr) { keys.push(key); } /L -- Lasse Reichstein Holst Nielsen 'Javascript frameworks is a disruptive technology'
From: Thomas 'PointedEars' Lahn on 20 Feb 2010 22:46
Lasse Reichstein Nielsen wrote: > laredotornado <laredotornado(a)zipmail.com> writes: >> Given an associative array, how do I get an array of the keys of that >> associative array? > > If arr is your associative array (i.e., an object) > In ECMAScript 5: > var keys = Object.keys(object) > In ECMAScript 3: > var keys = []; > for (var key in arr) { keys.push(key); } Where certain conditions must apply for the two approaches to be equivalent, of course. Let `o' be a reference to an object, JavaScript 1.7+ allows another variant, Array comprehension: var properties = [p for (p in o)]; BTW, for the property values you can use var values = [v for each (v in o)]; there, as a combination of the ECMA-262-3 extension (v1.7+) and the ECMA-357 implementation (v1.6+). Tested in Firefox/Iceweasel 3.5.8. PointedEars -- realism: HTML 4.01 Strict evangelism: XHTML 1.0 Strict madness: XHTML 1.1 as application/xhtml+xml -- Bjoern Hoehrmann |