Whatever benchmarking you do, you'll want to do it in you target JS
engine. Each engine (Trace/JaegerMonkey, V8, Nitro, Carakan, MS) will
perform different ops at different speeds. This is because some are
JIT based systems, some are tracing systems, some simple interpretors,
and some are combinations.
I'm a web-app developer by profession -- about 90% of my coding day is
spent working with JavaScript. Although I agree with Owen that it can
be confusing "getting it right", I would suggest that it's best
practice. If you're checking if something is null, then it's anyway
often simpler to just use shorthand: if(blah) { }. Remember,
undefined, null, 0, '', and false are all "falsy" values -- everything
else is truthy. That means that if you're after a true boolean when
checking if something's falsy, you can just use !!blah.
It's just my two cents, but, because JavaScript is such a flexible
language, I do believe that one should always be completely aware of
what's going on -- in other words, use === unless you very, very
specifically want to allow type coercion. It's kind of like falling
through in switch statemenrs: it canbe realky, really useful, or it
can cause really obscure, hard-to-track-down bugs, the latter being,
in my experience, more common than the former.
- Barry
www.barryvan.com.au
On Monday, March 15, 2010, David Mulder <[email protected]> wrote:
> When reading into this issue somebody suggested === would be faster than ==,
> I just finished running a very basic benchmark comparing == vs === as far as
> speed is concerned (string comparison). Unsurprisingly there isn't any speed
> difference, however the uncertainty of the results in === was far bigger
> (0.05 s with == and 0.3 s with ===), could anybody check whether this
> difference is reproducible or whether this is only some random problem with
> my system. (Tested with chromium on mac). I ran the following script 10 times
> for both == and ===, it's might be a bit simplistic, but there would have any
> big difference it should have come out.
>
> <script>start = (new Date()).getTime();string = "Lorem Ipsum is simply dummy
> text of the printing and typesetting industry. Lorem Ipsum has been the
> industry's standard dummy text ever since the 1500s, when an unknown printer
> took a galley of type and scrambled it to make a type specimen book. It has
> survived not only five centuries, but also the leap into electronic
> typesetting, remaining essentially unchanged. It was popularised in the 1960s
> with the release of Letraset sheets containing Lorem Ipsum passages, and more
> recently with desktop publishing software like Aldus PageMaker including
> versions of Lorem Ipsum.";
> string2 = "Lorem Ipsum is simply dummy text of the printing and typesetting
> industry. Lorem Ipsum has been the industry's standard dummy text ever since
> the 1500s, when an unknown printer took a galley of type and scrambled it to
> make a type specimen book. It has survived not only five centuries, but also
> the leap into electronic typesetting, remaining essentially unchanged. It was
> popularised in the 1960s with the release of Letraset sheets containing Lorem
> Ipsum passages, and more recently with desktop publishing software like Aldus
> PageMaker including versions of Lorem Ipsum.";
> for(i=0;i<10000;i++){ if(string===string2){ string=string+" ";
> string2=string2+" "; }
> }
> stop = (new Date()).getTime();console.log(stop-start);</script>
> David Mulder
> On Mon, Mar 15, 2010 at 4:20 PM, David Mulder <[email protected]> wrote:
>
> When reading into this issue somebody suggested === would be faster than ==,
> I just finished running a very basic benchmark comparing == vs === as far as
> speed is concerned (string comparison). Unsurprisingly there isn't any speed
> difference, however the uncertainty of the results in === was far bigger
> (0.05 s with == and 0.3 s with ===), could anybody check whether this
> difference is reproducible or whether this is only some random problem with
> my system. (Tested with chromium on mac). I ran the following script 10 times
> for both == and ===, it's might be a bit simplistic, but there would have any
> big difference it should have come out.
>
> <script>start = (new Date()).getTime();string = "Lorem Ipsum is simply dummy
> text of the printing and typesetting industry. Lorem Ipsum has been the
> industry's standard dummy text ever since the 1500s, when an unknown printer
> took a galley of type and scrambled it to make a type specimen book. It has
> survived not only five centuries, but also the leap into electronic
> typesetting, remaining essentially unchanged. It was popularised in the 1960s
> with the release of Letraset sheets containing Lorem Ipsum passages, and more
> recently with desktop publishing software like Aldus PageMaker including
> versions of Lorem Ipsum.";
>
> string2 = "Lorem Ipsum is simply dummy text of the printing and typesetting
> industry. Lorem Ipsum has been the industry's standard dummy text ever since
> the 1500s, when an unknown printer took a galley of type and scrambled it to
> make a type specimen book. It has survived not only five centuries, but also
> the leap into electronic typesetting, remaining essentially unchanged. It was
> popularised in the 1960s with the release of Letraset sheets containing Lorem
> Ipsum passages, and more recently with desktop publishing software like Aldus
> PageMaker including versions of Lorem Ipsum.";
>
> for(i=0;i<10000;i++){ if(string===string2){ string=string+" ";
> string2=string2+" ";
> } }
> stop = (new Date()).getTime();
> console.log(stop-start);</script>
> David Mulder
> On Mon, Mar 15, 2010 at 4:03 PM, Owen Taylor <--
http://barryvan.com.au/
[email protected]
--
http://barryvan.com.au/
[email protected]
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