On Jul 22, 8:15 pm, "Rob Desbois" <[EMAIL PROTECTED]> wrote:
> Stephan,
> The only time that == or != should be used (IMO anyway) is when you
> explicitly *want* type conversion to take place. Otherwise, it's safest (and
> faster) to use === or !==
The way i've always understood it (perhaps incorrectly) is that ===
and !== perform reference equality tests, such that ((new
String("foo")) !== (new String("foo"))). A quick test shows:
[EMAIL PROTECTED]:~$ SpiderApe -e "print( (new String('foo') === new
String('foo')))"
false
And yet:
[EMAIL PROTECTED]:~$ SpiderApe -e "print('foo' === 'foo')"
true
Weird.
(SpiderApe is simply an interpreter built on the SpiderMonkey engine -
http://SpiderApe.sf.net)
Given that, it's hard to predict how (typeof SomeUndefinedThing ===
"undefined") *should* behave, because we can show that String objects
and string literals are treated differently by ===, and we don't know
(philosophically speaking) which type of string typeof will return.
That said...
[EMAIL PROTECTED]:~$ SpiderApe -e "print(typeof NonExistent ===
'undefined')"
true
Hmmm. :/
