[dgreensp]

I'm surprised by the number of comments like this.

jQuery has to parse the selector and figure out that it's of the form "#id". This requires running a regular expression. A lot more is happening.

The whole jQuery call from start to finish takes 2.85 microseconds, in what is presumably a real benchmark, but microbenchmarks like this are hard to interpret and basically meaningless. But yes, if your app needs to do a burst of 350,000 jQuery calls in a tight loop and you are bummed that the whole thing takes a full second, you should then optimize using document.getElementById.

[lukeschlather]

> I'm surprised by the number of comments like this.

The sentiment is borne out by the facts when you dig a little deeper. Just calling document.getElementById without using the return value does not actually dig into the DOM and find the element according to this comment: http://news.ycombinator.com/item?id=4436438

[aneth4]

> if your app needs to do a burst of 350,000 jQuery calls in a tight loop and you are bummed that the whole thing takes a full second, you should then optimize using document.getElementById

Seems like you might have some other optimization work to do at that point :)