Boris Zbarsky, 2013-06-29 05:02 (Europe/Helsinki):
On 6/28/13 6:51 PM, Tab Atkins Jr. wrote:
querySelector is simply a more powerful querying function than the old
DOM methods,
And somewhat slower as a result, note.
If that's true, I would consider that as a bug. It should be really
simple for an UA implementation to optimize as following
querySelector("#foo") -> getElementById("foo")
querySelectorAll("foo") -> getElementsByTagName("foo")
as long the latter (internal) implementations were available and had
better performance.
Or, were you really talking about the difference between having to scan
the string given as a parameter to see if it looked like "simple"
selector that matches the old DOM method implementation? I understand
that JS+JIT allows faster method dispatching with getElementById() than
with querySelector() plus checking the characters of the first
parameter. I'd *guess* that that difference is meaningless compared to
walking the element tree or even doing hash lookup for the id which is
required to implement even the old DOM methods.
--
Mikko
