Comments on: How to use javascript hashes (or hash-table) http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/ Advanced katas for javascripters Fri, 30 Jul 2010 18:10:52 +0000 hourly 1 http://wordpress.org/?v=3.0 By: Nehagiri http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-925 Nehagiri Fri, 25 Jun 2010 15:29:15 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-925 very cooool! :-) very cooool! :-)

]]> By: Dan Dascalescu http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-767 Dan Dascalescu Sat, 18 Jul 2009 13:25:51 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-767 @nightfly: you can filter out properties inherited through the prototype chain using the <a>hasOwnProperty</a> Object method. @nightfly: you can filter out properties inherited through the prototype chain using the hasOwnProperty Object method.

]]> By: Nightfly http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-755 Nightfly Fri, 22 May 2009 22:14:01 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-755 Using objects as associative arrays have severe shortcomings in JS. It's ok and fast to use them when you just want to index into a set of data with a non-numeric key (string), but if you use libraries such as Prototype you can't iterate over the keys because those libraries add stuff to Object()'s prototype, making them properties of any objects you create and thus polluting your hash tables. You can use Prototype's (to stay with that lib) Hash object (http://prototypejs.org/api/hash) to work around this, but it's very slow compared to native objects. Using objects as associative arrays have severe shortcomings in JS.
It’s ok and fast to use them when you just want to index into a set of data with a non-numeric key (string), but if you use libraries such as Prototype you can’t iterate over the keys because those libraries add stuff to Object()’s prototype, making them properties of any objects you create and thus polluting your hash tables.
You can use Prototype’s (to stay with that lib) Hash object (http://prototypejs.org/api/hash) to work around this, but it’s very slow compared to native objects.

]]> By: web developer http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-711 web developer Mon, 16 Feb 2009 14:52:37 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-711 this is not a best way to create hash in javascript #var hashPetName = new Object(); #hashPetName["dog"] = “Rex”; #hashPetName["cat"] = “Mistigri”; use this instead var hashPetName={dog:'rex',cat:'Mistigri'}; this is not a best way to create hash in javascript

#var hashPetName = new Object();
#hashPetName["dog"] = “Rex”;
#hashPetName["cat"] = “Mistigri”;

use this instead
var hashPetName={dog:’rex’,cat:’Mistigri’};

]]> By: John http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-705 John Mon, 26 Jan 2009 19:42:55 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-705 Hello dude, Thanks a lot for this post. I really need this one in my project. Thank you once again...... Hello dude, Thanks a lot for this post. I really need this one in my project. Thank you once again……

]]> By: Thomas http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-704 Thomas Fri, 16 Jan 2009 17:31:36 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-704 Hi Dan, thanks a lot. It really helpt me to understand how objects work in JS. And: “Only valid key types are number and String”. That's also fine with me Cheers, Thomas Hi Dan,

thanks a lot.
It really helpt me to understand how objects work in JS.

And: “Only valid key types are number and String”.
That’s also fine with me

Cheers, Thomas

]]> By: Manuel http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-694 Manuel Mon, 29 Dec 2008 19:18:37 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-694 "Only valid key types are number and String". That is very ok for me! Thanks Dan. “Only valid key types are number and String”.

That is very ok for me!

Thanks Dan.

]]> By: Dan http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-56 Dan Mon, 02 Apr 2007 17:25:50 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-56 Thanks! I subscribed to the mailing list. Thanks! I subscribed to the mailing list.

]]> By: Michael Greenberg http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-55 Michael Greenberg Mon, 02 Apr 2007 15:35:34 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-55 Well, without a notion of (semi-)unique object id, there's not much to be done. If you look at the <a href="https://mail.mozilla.org/listinfo/es4-discuss" rel="nofollow">ES4 discussion list</a>, you'll see that they've come up with intrinsic::hashcode, which computes a non-unique object id. You could implement a bucket hash table with that, but they don't provide one out of the box. The mailing list is open and (from what I'm told) pretty receptive. So if you need hash tables for something, by all means mention it. Well, without a notion of (semi-)unique object id, there’s not much to be done. If you look at the ES4 discussion list, you’ll see that they’ve come up with intrinsic::hashcode, which computes a non-unique object id. You could implement a bucket hash table with that, but they don’t provide one out of the box.

The mailing list is open and (from what I’m told) pretty receptive. So if you need hash tables for something, by all means mention it.

]]> By: Dan http://www.javascriptkata.com/2007/03/29/how-to-use-javascript-hashes/comment-page-1/#comment-54 Dan Mon, 02 Apr 2007 13:22:51 +0000 http://javascriptkata.timmyontime.com/?p=18#comment-54 Michael, how can we do hash table less terrible? Michael, how can we do hash table less terrible?

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