Most appropriate way to get this: $($(".answer")[0])
I can't speak to the elegance aspect, but the performance aspect here actually can make a huge difference.
It looks like, from a set of JavaScript testing, that your original method is actually the most efficient one, and contrary to the hypothesizing that the accepted answer linked to, non-CSS Sizzle selectors tend to be much less efficient than method selectors. There's a reason for that. The $('.answer') can use the browser native getElementsByClass() without having to manually traverse the results. The :first selector complicates that. In this instance, using the sizzle selectors seems to slow the selection by a factor of between 4-5.
I'd argue that, with jQuery, performance should trump elegance, and all evidence (every single browser I've tested so far!) seems to indicate that OP's inelegant solution is the fastest by a fair amount.
Here are the results of the browsers with the most test runs:
(The numbers are 'operations per second', so higher numbers are faster, lower numbers are slower.)
The following are all equivalent in functionality (though not speed):
var a0 = $($('.answer')[0]);var a0 = $('.answer').first();- see http://api.jquery.com/first/var a0 = $('.answer:first');- see http://api.jquery.com/first-selector/var a0 = $('.answer').eq(0);- see http://api.jquery.com/eq/var a0 = $('.answer:eq(0)');- see http://api.jquery.com/eq-selector/
Which is the best?
It has been hypothesized that the selector versions should be faster than the method versions (and the logic makes some sense) but I have not yet found a reliable cross-browser, multi-document benchmark that proves this to be true.
And in some cases you cannot use the selector, as you have a jQuery object resulting from chained results and must later pare it down.
Edit: Based on the excellent information from @yc's tests below, following are the current (2011-Feb-4) test results summarized and compared against a baseline of .answer:first:
:first :eq(0) .first() .eq(0) $($('...')[0])Chrome 8+ 100% 92% 224% 266% 367% FF 3.6 100% 100% 277% 270% 309% FF 4.0b 100% 103% 537% 521% 643% Safari 5 100% 93% 349% 352% 467% Opera 11 100% 103% 373% 374% 465% IE 8 100% 101% 1130% 1246% 1767% iPhone 4 100% 95% 269% 316% 403%===================================================== Weighted 100% 92% 286% 295% 405% Major 100% 95% 258% 280% 366%- The Weighted line shows the performance weighted by the number of tests per browser; popular browsers (among those testing) are counted more strongly.
- The Major line shows the same, only including non-beta releases of the major desktop browsers.
In summary: the hypothesis is (currently) wrong. The methods are significantly faster than the Sizzle selectors, and with almost no exception the OP's code $($('.answer')[0]) is the fastest of them all!