Comments on: Tip: getting values from an options list

By: Cloudgen

Cloudgen — Fri, 14 May 2010 01:56:49 +0000

Less code means less bandwidth and more efficiency in usage of cache for high traffic website (less hacking risk, less risk in DDOS attack, etc). Let’s client’s computers do the rest (that’s the philosophy of Client-Side Javascript). So, as a software engineer from a B2B firm, I prefer one line version:

var values=$.map($(‘#mySelectElement’)[0].options, function(n){return n.value});

By: caphun

caphun — Thu, 22 Oct 2009 09:38:32 +0000

@dalin: Yes, definitely. Using values[] would be quicker than push but in most cases you won’t notice. If I were wearing my optimization hat I’d also use document.getElementById('mySelectElement') to add to that.

jQuery.map at its heart is a for loop with a callback. That’s all it is. I see option one as a common pattern we run into often and option 2 as a possible solution to that pattern.

By: dalin

dalin — Thu, 22 Oct 2009 07:06:36 +0000

If this was PHP I would say “bad idea”. But I know much less about JavaScript so perhaps it’s not.

in option 1 you use language constructs (I would think it would be even better to use values[] rather than the method .push). In option 2 you use a method to run a callback function on each element. I’m guessing there’s an order of magnitude difference in performance (if not more). Albeit with a select box there’s probably not too many options to iterate through, but other scenarios may have significantly more.