[pooriaazimi]

Question: is the 'Speed Comparison' for real? I find it really, really hard to believe. Surely jQuery & co. revert to native implementations (if they exists, as they do in all modern browsers) for things like `document.getElementById` and don't iterate over the whole DOM.

[masklinn]

> is the 'Speed Comparison' for real?

Depends what you mean by "for real". The document.getElementsByTagName comparison is bullshit: gEBTN is lazy, just calling it basically doesn't do any work, it just allocates a NodeList object and returns.

If you serialize the nodelist to an array or use document.querySelector instead (it returns an array) you get ~3x between the native version and the slowest libraries, not 400x.

[Timmy_C]

Yeah, Sizzle will grab an element using `document.getElementById()` but only after checking the nodeType of the context, ensuring the selector is a string and running the selector through a regular expression.

[jfaucett]

I just looked at the latest jquery and its each statement does not do a native fallback, which really surprised me. Also you have to keep in mind that a simple $('a.active').each(someFunc), has to run through the a lot of jq luggage, plus the initial http fetch of the library (which has come under criticism for its size).