http://code.google.com/p/jslibs/wiki/JavascriptTips

Most of em are pretty straightforward, but certainly almost everyone are pretty advanced.

Some are pretty neat tricks.

I had trouble with this one

closures pitfall

var a = [];

for ( var i=0; i<10; i++ ) {

a[i] = function() { Print(i); }
}

a[0](); // is 10
a[1](); // is 10
a[2](); // is 10
a[3](); // is 10

Var explicitly sets the scope of i inside the for loop. Why then a[0] == 10?

Firebug is a bless for this kind of things :)

When I don't have firebug or any other debugger at hand, this is the most useful construct to find those nasty bugs.

for ( var i in function(){ return [1,2,3] }() )
  Print(i)


Or my version

t = "";
for (i in suchvar)
  t += i + " = " + suchvar[i] + "\n";
alert(t);

Is there a misprint in your example?

Like what?

Maybe just missing info... like what does function() do?

I'm not a java guy.

Since the assignment is coming from function(), I can't really explain why a[0] is anything at all.

I'm just taking your word that a[0-5] = 10.

Is Javascript. In javascript everything is an object, even functions.

So if you do

a = function(){}

"a" will be an empty function. A little bit like function pointers in C++.

You can even create an array of functions

a = [ function(){return 1}, function(){return 2}]

so

a[0]() will return 1
a[1]() will return 2


Also search for closures. Pretty good stuff :)

Ahh.

So it is because the loop always ends at 10 and wherever you end up evaluating a[x] it is always going to amount to Print(10) once the loop has completed?

Yeah, something like that.
a[i] is evaluated inside the loop
Print(i) is evaluated when the function executes

My mistake was to think that

for (var i...

Would make i's scope local inside the for loop. That's not the case. I becomes global, so it can be evaluated later.

Also, this is an obligated lecture  to understand closures

http://www.jibbering.com/faq/faq_notes/closures.html

You will find those concepts on lisp or in lambda programming (whatever that means :P)

Is there a Javascript compiler? Or cross-compiler into C?

ultimate js tip: dont use js

Did you get from bed at the wrong side today iwan? Or you didn't get laid last night?

iguess both

You can always get even with good wake up sex.

Works for me :)

When and where, Masiosare?