Rails - Jun 2010 - What kind of Ruby / Erb is allowed inside HAML's :javascript

It seems that inside of HAML''s :javascript filter, no Ruby code is
allowed, not even a comment.

So this is NOT allowed:

:javascript
  - 1.upto(10) do |i|

:javascript
  -# just a comment not to show to public

(somebody said there is not way to hide comment like that inside a
:javascript filter.  Is that true?

but it seems the only thing allowed is

:javascript
  $(''#aDiv'').html(''#{a_ruby_variable}'';

only this #{ } is allowed.  Nothing else that is Ruby is allowed?
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Jian Lin wrote:
> but it seems the only thing allowed is
> 
> :javascript
>   $(''#aDiv'').html(''#{a_ruby_variable}'';
correction:  (missing the ending paren)

    :javascript
      $(''#aDiv'').html(''#{a_ruby_variable}'');

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Jian Lin wrote:
> It seems that inside of HAML''s :javascript filter, no Ruby code is
> allowed, not even a comment.
I believe that''s correct.  But you should never need Ruby within 
JavaScript, nor should you ever need JavaScript within HTML (it''s best 
to put it in a separate file).
> 
> So this is NOT allowed:
> 
> :javascript
>   - 1.upto(10) do |i|
> 
> :javascript
>   -# just a comment not to show to public
> 
> (somebody said there is not way to hide comment like that inside a
> :javascript filter.  Is that true?
Probably.
> 
> but it seems the only thing allowed is
> 
> :javascript
>   $(''#aDiv'').html(''#{a_ruby_variable}'';
> 
> only this #{ } is allowed.  Nothing else that is Ruby is allowed?
I''m surprised that #{} works here.

If you think you need Ruby in your JS, you''ve got a design problem. 
Fix
it.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org

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Marnen Laibow-Koser wrote:
> 
> If you think you need Ruby in your JS, you''ve got a design
problem.  Fix
> it.
i can think of a few cases where Ruby might be wanted inside of 
Javascript output:

1) -# to add comment but not to show it to the public
2) using if else to output something based on some condition
3) using loop
4) providing values to javascript code by json


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Jian Lin wrote:
> Marnen Laibow-Koser wrote:
>> 
>> If you think you need Ruby in your JS, you''ve got a design
problem.  Fix
>> it.
> 
> i can think of a few cases where Ruby might be wanted inside of 
> Javascript output:
And all of them represent design problems and are better handled in 
other ways.
> 
> 1) -# to add comment but not to show it to the public
Use a JS minifier.
> 2) using if else to output something based on some condition
> 3) using loop
Use JavaScript control structures for these, not Ruby control 
structures.
> 4) providing values to javascript code by json
Put the JSON in a (hidden) div, have the JavaScript read its content.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
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Marnen Laibow-Koser wrote:
>> 1) -# to add comment but not to show it to the public
> 
> Use a JS minifier.
> 
>> 2) using if else to output something based on some condition
>> 3) using loop
> 
> Use JavaScript control structures for these, not Ruby control 
> structures.
> 
>> 4) providing values to javascript code by json
> 
> Put the JSON in a (hidden) div, have the JavaScript read its content.
JS Minifier when there are 5 lines of code?

Also, I think we can always do things another way... but just that why 
embedding values from Ruby to Javascript is bad, while hiding them first 
in a div and read it back from the div is good?   (suppose they are 
simple keywords from our db which keywords like "shirt",
"shorts",
"jacket" which will not cause any javascript injection by user input.)


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Jian Lin wrote:
> Marnen Laibow-Koser wrote:
> 
>>> 1) -# to add comment but not to show it to the public
>> 
>> Use a JS minifier.
>> 
>>> 2) using if else to output something based on some condition
>>> 3) using loop
>> 
>> Use JavaScript control structures for these, not Ruby control 
>> structures.
>> 
>>> 4) providing values to javascript code by json
>> 
>> Put the JSON in a (hidden) div, have the JavaScript read its content.
> 
> JS Minifier when there are 5 lines of code?
If there are only 5 lines of code, why do you need private comments in 
the first place?
> 
> Also, I think we can always do things another way...
Yes.
> but just that why 
> embedding values from Ruby to Javascript is bad, while hiding them first 
> in a div and read it back from the div is good?
Because it separates the Ruby and JavaScript more cleanly.  This makes 
the code more maintainable, and also improves performance by allowing 
the client to cache one JavaScript file instead of the server having to 
regenerate it for each call.
>   (suppose they are 
> simple keywords from our db which keywords like "shirt",
"shorts",
> "jacket" which will not cause any javascript injection by user
input.)
Then they should still be handled in the way I suggested.  Dynamically 
generating JavaScript is almost always a bad thing.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
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Marnen Laibow-Koser wrote:
>> JS Minifier when there are 5 lines of code?
> 
> If there are only 5 lines of code, why do you need private comments in 
> the first place?
Do you often see other people''s way of doing things needing to abide to
your rule book?  Such as: if there are only n lines of Javascript code, 
they shall never have private comments there.



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Jian Lin wrote:
> Marnen Laibow-Koser wrote:
> 
>>> JS Minifier when there are 5 lines of code?
>> 
>> If there are only 5 lines of code, why do you need private comments in 
>> the first place?
> 
> Do you often see other people''s way of doing things needing to
abide to
> your rule book?  Such as: if there are only n lines of Javascript code, 
> they shall never have private comments there.
You missed my point.  It wasn''t "shall never".  My point was
this: a
5-line routine should normally not need comments.  If you need comments 
on something that short, perhaps your code isn''t as clearly written as 
it should be...


Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org

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Marnen Laibow-Koser wrote:
> Jian Lin wrote:
>> Marnen Laibow-Koser wrote:
>> 
>>>> JS Minifier when there are 5 lines of code?
>>> 
>>> If there are only 5 lines of code, why do you need private comments
in
>>> the first place?
>> 
>> Do you often see other people''s way of doing things needing to
abide to
>> your rule book?  Such as: if there are only n lines of Javascript code,
>> they shall never have private comments there.
> 
> You missed my point.  It wasn''t "shall never".  My point
was this: a
> 5-line routine should normally not need comments.  If you need comments 
> on something that short, perhaps your code isn''t as clearly
written as
> it should be...
A reason may be, a comment that says "TODO: we don''t have enough
time to
do more than this right now.  talk to Simon for when it will be done" -- 
or any other similar comment -- may not be totally appropriate for the 
public.
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Jian Lin wrote:
[...]
> 
> A reason may be, a comment that says "TODO: we don''t have
enough time to
> do more than this right now.  talk to Simon for when it will be done"
--
> or any other similar comment -- may not be totally appropriate for the 
> public.
I see your point about TODO comments.  But the fundamental problem here 
is that your client-side JS has to be delivered to the client to get 
run.  If there are things in the JS that your client shouldn''t see,
then
you need a minifier or an obfuscator.

Or...hmm.  Check out CoffeeScript; it''s a bit like Haml for JS.

Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org
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Marnen Laibow-Koser wrote:
> 
> Or...hmm.  Check out CoffeeScript; it''s a bit like Haml for JS.
if only there is a Ruby to JS converter.

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Jian Lin wrote:
> Marnen Laibow-Koser wrote:
> 
>> 
>> Or...hmm.  Check out CoffeeScript; it''s a bit like Haml for
JS.
> 
> if only there is a Ruby to JS converter.
Well, there''s RJS and CoffeeScript.  But Ruby and JS work very 
differently.  My advice is to write each one directly rather than 
relying on converters.

 Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen-sbuyVjPbboAdnm+yROfE0A@public.gmane.org


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