Re: [jQuery] New Dev center by Opera
>> Object wrappers are a minefield because they sometimes don't behave
>> the same as their primitive type. For example, eval() won't work if
>> called with a "new String" argument, and "new Boolean(false)"
>> evaluates to TRUE in a conditional context because it's an object.
>
> new Boolean(false) becomes false, but new Boolean('false') becomes true.
> Or did I get that wrong?
>
> http://www.jibbering.com/faq/faq_notes/type_convert.html#tcBool
It's not a type conversion, it's the object wrapping that causes havoc.
Boolean(false) returns its argument converted to a primitive boolean type;
new Boolean(false) converts its argument and wraps it in a Boolean object.
Copy/paste this into your favorite browser address bar:
javascript:b=Boolean(false); if(b) alert("true=="+b);else
alert("false=="+b);
Completely expected output, right? Now, add "new" to create a Boolean
object:
javascript:b=new Boolean(false); if(b) alert("true=="+b);else
alert("false=="+b);
Any object in a conditional context is considered to be true, even a Boolean
_object_ with a false value. However, when it comes time to print the value,
the .toString() method pulls out the actual value.
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Re: [jQuery] New Dev center by Opera
Dave Methvin schrieb:
> Object wrappers are a minefield because they sometimes don't behave the same
> as their primitive type. For example, eval() won't work if called with a
> "new String" argument, and "new Boolean(false)" evaluates to TRUE in a
> conditional context because it's an object.
new Boolean(false) becomes false, but new Boolean('false') becomes true.
Or did I get that wrong?
http://www.jibbering.com/faq/faq_notes/type_convert.html#tcBool
-- Klaus
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Re: [jQuery] New Dev center by Opera
> http://dev.opera.com/articles/view/48/
>
> I didn't know that this:
> var s = new String('0123456789');
> for( var i = 0; i < s.length; i++ ) {
> s.charAt(i);
> }
>
> [is faster than?--dm] this:
> var s = '0123456789';
> for( var i = 0; i < s.length; i++ ) {
> s.charAt(i);
> }
> because of the implicit object conversion involved.
Optimizations based on Opera may go the wrong way for a majority of users.
For example, here are some hard millisecond numbers from a test of that
example:
Object string
Opera 9: 344 406
FF 1.5: 18592703
IE6: 640 453
So, it's blazingly fast either way in Opera, faster to use a string in IE,
and a choice between slow and horribly slow in Firefox. Perhaps a difference
in memory usage would justify it if the string was extremely long?
Object wrappers are a minefield because they sometimes don't behave the same
as their primitive type. For example, eval() won't work if called with a
"new String" argument, and "new Boolean(false)" evaluates to TRUE in a
conditional context because it's an object.
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Re: [jQuery] New Dev center by Opera
> And by the way: the site is not centered on developing for/with Opera.
True. I didn't want to hijack your thread for an Opera discussion. The
"Efficient Javascript" article is really a good read:
http://dev.opera.com/articles/view/48/
I didn't know that this:
var s = new String('0123456789');
for( var i = 0; i < s.length; i++ ) {
s.charAt(i);
}
then this:
var s = '0123456789';
for( var i = 0; i < s.length; i++ ) {
s.charAt(i);
}
because of the implicit object conversion involved. There is a lot of stuff
that could be used to improve the jQuery core performance.
--
Jörn Zaefferer
http://bassistance.de
--
GMX DSL-Flatrate 0,- Euro* - Überall, wo DSL verfügbar ist!
NEU: Jetzt bis zu 16.000 kBit/s! http://www.gmx.net/de/go/dsl
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Re: [jQuery] New Dev center by Opera
Jörn Zaefferer schrieb: >> There's not nearly enough publicity about Opera for my liking. What, with >> it >> being a more powerful browser than Firefox and all... > > It's build-in adblocker can't compete with FF's extension adblocker. Sad, but > the main reason I'm not using Opera most of the time. Really? I'm using Firefox because for developing I think it has the better plugins (tools). But Opera is catching up there, and honestly, maybe I just don't know the right tools for Opera... For private use I'm using Flock because I love the del.icio.us integration. And by the way: the site is not centered on developing for/with Opera. -- Klaus ___ jQuery mailing list discuss@jquery.com http://jquery.com/discuss/
Re: [jQuery] New Dev center by Opera
Ahh... But is the built in adblocker in Opera better than Firefox without one?! I mean, how many ads does Firefox block without the adblocker installed... And how many does Opera block by default?! Jörn Zaefferer wrote: > >> There's not nearly enough publicity about Opera for my liking. What, with >> it >> being a more powerful browser than Firefox and all... > > It's build-in adblocker can't compete with FF's extension adblocker. Sad, > but the main reason I'm not using Opera most of the time. > > -- > Jörn Zaefferer > > http://bassistance.de > -- > GMX DSL-Flatrate 0,- Euro* - Überall, wo DSL verfügbar ist! > NEU: Jetzt bis zu 16.000 kBit/s! http://www.gmx.net/de/go/dsl > > ___ > jQuery mailing list > discuss@jquery.com > http://jquery.com/discuss/ > > -- View this message in context: http://www.nabble.com/New-Dev-center-by-Opera-tf2586811.html#a7215110 Sent from the JQuery mailing list archive at Nabble.com. ___ jQuery mailing list discuss@jquery.com http://jquery.com/discuss/
Re: [jQuery] New Dev center by Opera
> There's not nearly enough publicity about Opera for my liking. What, with > it > being a more powerful browser than Firefox and all... It's build-in adblocker can't compete with FF's extension adblocker. Sad, but the main reason I'm not using Opera most of the time. -- Jörn Zaefferer http://bassistance.de -- GMX DSL-Flatrate 0,- Euro* - Überall, wo DSL verfügbar ist! NEU: Jetzt bis zu 16.000 kBit/s! http://www.gmx.net/de/go/dsl ___ jQuery mailing list discuss@jquery.com http://jquery.com/discuss/
Re: [jQuery] New Dev center by Opera
Cheers! There's not nearly enough publicity about Opera for my liking. What, with it being a more powerful browser than Firefox and all... Klaus Hartl-3 wrote: > > Hi all, > > this is not exactly jQuery related, but there's a new Dev center by > Opera, and as one could expect from them there are already some nice > articles online. > http://dev.opera.com/ > > > Worth reading for example: Efficient JavaScript: > http://dev.opera.com/articles/view/48/ > > > -- Klaus > > ___ > jQuery mailing list > discuss@jquery.com > http://jquery.com/discuss/ > > -- View this message in context: http://www.nabble.com/New-Dev-center-by-Opera-tf2586811.html#a7214677 Sent from the JQuery mailing list archive at Nabble.com. ___ jQuery mailing list discuss@jquery.com http://jquery.com/discuss/
[jQuery] New Dev center by Opera
Hi all, this is not exactly jQuery related, but there's a new Dev center by Opera, and as one could expect from them there are already some nice articles online. http://dev.opera.com/ Worth reading for example: Efficient JavaScript: http://dev.opera.com/articles/view/48/ -- Klaus ___ jQuery mailing list discuss@jquery.com http://jquery.com/discuss/
