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Re: Why is querySelector much slower?

From: Jonas Sicking <jonas@sicking.cc>
Date: Mon, 27 Apr 2015 19:04:27 -0700
Message-ID: <CA+c2ei_01rJOQr2w-cGPm7sAQ1642KegkoFJ7inQNUqvt29kDQ@mail.gmail.com>
To: Glen Huang <curvedmark@gmail.com>
Cc: public-webapps <public-webapps@w3.org>
On Mon, Apr 27, 2015 at 1:57 AM, Glen Huang <curvedmark@gmail.com> wrote:
> Intuitively, querySelector('.class') only needs to find the first matching
> node, whereas getElementsByClassName('.class')[0] needs to find all matching
> nodes and then return the first. The former should be a lot quicker than the
> latter. Why that's not the case?

I can't speak for other browsers, but Gecko-based browsers only search
the DOM until the first hit for getElementsByClassName('class')[0].
I'm not sure why you say that it must scan for all hits.

/ Jonas
Received on Tuesday, 28 April 2015 02:05:25 UTC

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