Need some JavaScript puzzles

[Jorge]

Re: Need some JavaScript puzzles

On Sep 27, 4:07 am, Conrad Lender <crlen...@yahoo .comwrote:

On 2008-09-27 03:18, Jorge wrote:
>

Define function add such that>
     add(3)(4)
returns 7.

>

javascript:aler t((function add (p) { var a=p; return function (p)
{ return a+p } })(3)(4))

>
You don't need to create an extra variable.
>
function add (first) {
    return function (second) {
        return first + second;
    }
>
}

Damn it!
(but that took you an hour hehe)

--
Jorge.

[Oltmans]

Re: Need some JavaScript puzzles

On Sep 27, 7:07 am, Conrad Lender <crlen...@yahoo .comwrote:

On 2008-09-27 03:18, Jorge wrote:
>

Define function add such that>
     add(3)(4)
returns 7.

>

javascript:aler t((function add (p) { var a=p; return function (p)
{ return a+p } })(3)(4))

>
You don't need to create an extra variable.
>
function add (first) {
    return function (second) {
        return first + second;
    }
>
}
>
But hey!
Don't spoil the fun for the OP by posting the solution!
>
@Douglas:
I'd also appreciate more puzzles if you know any. This kind of (simple
but interesting) problem is a godsend when you're teaching kids.

I absolutely agree with you. We need some puzzles like that. I really
liked that puzzle. This is exactly the kind of puzzle that I wanted to
solve. I mean a puzzle that would force me hard to think about the
language constructs and this one just did that.

Also, I thank others who posted their invaluable comments.

>
The only thing I've seen recently that comes close to a puzzle is this
website:
>
 http://parentnode.org/static/challange2.html
>
You need to enter the correct password, that's all. No rewards :-) It's
not pretty, rather the opposite, but if you like obfuscation, it might
be interesting. Syntax highlighting helps.
>
  - Conrad

[Oltmans]

Re: Need some JavaScript puzzles

On Sep 27, 6:08 am, Douglas Crockford <nos...@sbcglob al.netwrote:

Oltmans wrote:

Hi guys,
I'm learning JavaScript and I need some puzzles that can make me a
better JavaScript programmer.

>
Dmitri showed me this one:
>
Define function add such that
>
     add(3)(4)
>
returns 7.

Douglas,
I really appreciate you jumping in the discussion. I really was
looking for such a puzzle that can force me think hard about language
constructs and that one just did that. There are many puzzles that you
can solve to improve your algorithmic skills but I was not looking for
those. And I guess your puzzle was dead on. I agree with other people
i.e. if you know more such puzzles like that then please let us know.
Any puzzles that will make me think hard about how to use the
JavaScript constructs. Please post more such puzzles. It will be a lot
of fun. Thanks again.

P.S: You're my JavaScript hero :) I'm even on the verge of finishing
"Little Schemer" just because you recommended it.

[Conrad Lender]

Re: Need some JavaScript puzzles

On 2008-09-28 02:08, Oltmans wrote:

I absolutely agree with you. We need some puzzles like that. I really
liked that puzzle. This is exactly the kind of puzzle that I wanted to
solve. I mean a puzzle that would force me hard to think about the
language constructs and this one just did that.

This page has a number of short brain teasers:

http://dow.ngra.de/2008/02/28/javascript-puzzlers/

A few caveats:
- The examples assume that a print() function has been defined, which
is usually not the case in a browser environment (Rhino does have a
print() function though).
- The later examples build on the results of the previous ones, meaning
that they are not self-contained.

IIRC that page has even been posted here before.


- Conrad

[=?ISO-8859-1?Q?Karl_Tikj=F8b_Krukow?=]

Re: Need some JavaScript puzzles

Oltmans wrote:

Hi guys,
I'm learning JavaScript and I need some puzzles that can make me a
better JavaScript programmer.

I think the best way for you to learn JavaScript depends on your
background. What other programming languages do you already know well?

[dhtml]

Re: Need some JavaScript puzzles

Jorge wrote:

On Sep 24, 3:14 am, dhtml <dhtmlkitc...@g mail.comwrote:

>1. write a function return the binary representation of a given number
>in "ON" and "OFF". For example, if the input is 47 (101111 in binary),
>it should return "ON OFF ON ON ON ON".

>

http://preview.tinyurl.com/3unmha

>

You could have used toString(radix) .

var n = 101111;

n.toString(2).r eplace(/1/g, "ON ").
replace(/0/g,"OFF ").replace(/ $/,'');


Garrett

--
Jorge.

[Peter Michaux]

Re: Need some JavaScript puzzles

On Sep 23, 8:50 am, Oltmans <rolf.oltm...@g mail.comwrote:

Hi guys,
I'm learning JavaScript and I need some puzzles that can make me a
better JavaScript programmer. I mean I'm looking out for programming
puzzles (e.g. Project Euler or TopCoder) but I'm looking out for
language specific puzzles that can make me a top-notch JavaScript
programmer. a) Any puzzles you can recommend? b) Any programs that you
can suggest that can make me learn JavaScript internals in greatest
depth.
>
Please recommend anything. I know some very best programmers lurk
around here so any help will be appreciated. Moreover, to people
who've been using JavaScript for sometime, please recommend programs
that you wish you had done earlier to understand internals in a better
way. Thanks in advance.

I highly recommend the following thread starting with this post:

http://groups.google.com/group/comp.lang.javascript/msg/28559592272d4e54

The whole thread is

http://groups.google.com/group/comp.lang.javascript/browse_frm/thread/9848ec5004c19c97/28559592272d4e54

Peter

[Jorge]

Re: Need some JavaScript puzzles

On Sep 28, 9:04 pm, dhtml <dhtmlkitc...@g mail.comwrote:

Jorge wrote:

On Sep 24, 3:14 am, dhtml <dhtmlkitc...@g mail.comwrote:

1. write a function return the binary representation of a given number
in "ON" and "OFF". For example, if the input is 47 (101111 in binary),
it should return "ON OFF ON ON ON ON".

>

http://jorgechamorro.com/cljs/016/

>
You could have used toString(radix) .
>
var n = 101111;
>
n.toString(2).r eplace(/1/g, "ON ").
replace(/0/g,"OFF ").replace(/ $/,'');
>

Now that you say it... yes. I completely forgot its existence :-)

Thanks for posting that because I have played with it a little and I
have learnt that it converts reals as well:

(3.1416).toStri ng(2) ->
11.001001000011 111111100101110 010010001110100 010100111

and that it will fail as miserably as mine and without warning (for
those numbers that a 'number' primitive value can't represent
accurately):

javascript:aler t((900719925474 0991).toString( 2)) ->
111111111111111 111111111111111 111111111111111 11111111
javascript:aler t((900719925474 0991.4).toStrin g(2))->
111111111111111 111111111111111 111111111111111 11111111
javascript:aler t((900719925474 0991.5).toStrin g(2))->
100000000000000 000000000000000 000000000000000 000000000
javascript:aler t((900719925474 0992).toString( 2)) ->
100000000000000 000000000000000 000000000000000 000000000
javascript:aler t((900719925474 0993).toString( 2)) ->
100000000000000 000000000000000 000000000000000 000000000


While writing 'my version', I was going to 'logically' test the bits
with an '&', but I have discovered that the & operator operates on
just 32 bits, not on the 53 available in the mantissa of a 'number'
primitive value:

javascript:aler t(9007199254740 991 & Math.pow(2,31)) ===
-100000000000000 000000000000000 00
javascript:aler t(9007199254740 991 & Math.pow(2,32)) === 0

--
Jorge.

[Dr J R Stockton]

Re: Need some JavaScript puzzles

On Sep 29, 9:02 pm, Jorge <jo...@jorgecha morro.comwrote:

While writing 'my version', I was going to 'logically' test the bits
with an '&', but I have discovered that the & operator operates on
just 32 bits, not on the 53 available in the mantissa of a 'number'
primitive value:

Agreed, but one can access all bits of a Double for logical operations
by using arithmetic. Working example :
<URL:http://www.merlyn.demo n.co.uk/js-misc0.htm#TC>

--
(c) John Stockton, near London, UK. Posting with Google.
Mail: J.R.""""""""@ph ysics.org or (better) via Home Page at
Web: <URL:http://www.merlyn.demo n.co.uk/>
FAQish topics, acronyms, links, etc.; Date, Delphi, JavaScript, ....|

[Jorge]

Re: Need some JavaScript puzzles

On Sep 29, 11:49 pm, Dr J R Stockton <J.R.Stock...@p hysics.orgwrote :

On Sep 29, 9:02 pm, Jorge <jo...@jorgecha morro.comwrote:
>

While writing 'my version', I was going to 'logically' test the bits
with an '&', but I have discovered that the & operator operates on
just 32 bits, not on the 53 available in the mantissa of a 'number'
primitive value:

>
Agreed, but one can access all bits of a Double for logical operations
by using arithmetic.  Working example :
<URL:http://www.merlyn.demo n.co.uk/js-misc0.htm#TC>

Yes, that's what I did, see:

function toBinaryString (number) {
var weight= Math.pow(2, 52), binStr= '', decimalPoint;
do {
if (number >= weight) {
number-= weight;
binStr+= '1';
} else { binStr+= binStr ? '0' : ''; }

if (((weight/= 2) < 1) && !decimalPoint) {
decimalPoint= 1;
if (number) {
binStr+= binStr ? '.' : '0.';
} else { binStr+= binStr ? '' : '0'; }
}
} while (!decimalPoint || (number && weight))
return binStr;
};

--
Jorge.

[Jorge]

Re: Need some JavaScript puzzles

On Sep 27, 3:08 am, Douglas Crockford <nos...@sbcglob al.netwrote:

>
Dmitri showed me this one:
>

http://dmitry.baranovskiy.com/

http://raphaeljs.com/

http://vimeo.com/1815045

--
Jorge.