spikex/quiz-1.md

## quiz-1.md

      
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              quiz-1.md
            
          
    So you think you wanna be a web developer...

Fork this, update your copy with answers.

They don't need to be precise - pseudo-code is fine in most cases.

Some questions don't have correct answers.


Submit your answers to ara@dojo4.com


  FROM: you@yeraaddy.com

  SUBJECT: [dojo4-quiz] quiz-1

  BODY:

    https://gist.github.com/to-your-submission


==========================================================

is this broken in html5? if so why?
==========================================================

  <div id='teh_javascripts' />

teh answerz...
In HTML5 <div/> == <div> not <div></div>
==========================================================
2. write an http GET request for the url

  'http://domain.com:4242/foo/bar/baz.html'


teh answerz...
require 'open-uri'
response = open('http://domain.com:4242/foo/bar/baz.html')
curl 'http://domain.com:4242/foo/bar/baz.html'
==========================================================
3. in any language you choose, write this to run in parallel

  numbers = 20, 1

  results = []

  numbers.each do |number|
    results.push( parallelize{ number * 2 } )
  end


  sum = reduce( results )


teh answerz...
numbers = 20, 1

results = []
threads = []

numbers.each do |number|
  threads << Thread.new { results << number * 2 }
end

threads.each { |t| t.join }

sum = results.reduce(:+)
==========================================================
4. in any language you choose, write this to run in parallel on multiple cores

  numbers = 20, 1

  results = []

  numbers.each do |number|
    results.push( parallelize{ number * 2 } )
  end


  sum = reduce( results )


teh answerz...
Seems like it depends a lot on the Ruby interpreter, but I suspect that using thread local variables, as follows, would make it more likely.
numbers = 20, 1

results = []
threads = []

numbers.each do |number|
  threads << Thread.new { Thread.current['result'] = number * 2 }
end

sum = threads.reduce(0) { |sum,thread| thread.join ; sum + thread['result']}
==========================================================
5. is this broken in html5?, why?

  <label for='user.email'>
  <input name='user.email'>

teh answerz...
"for" needs to refer to an element id, not a name.
==========================================================
6. what is value of 'status'

  if @not_modified
    render :status => status
  end

teh answerz...
Without additional code, it's undefined.
==========================================================
7. is this javascript broken?  if so, why?

  var submit = document.getElementById("submit");

  submit.click();

teh answerz...
Dunno. .click() didn't always exists, but it seems to work in modern browsers.
==========================================================
8. which is better?  why?

<!-- A -->

  <table>
    <tr>
      <td class='key' style='width:33%'>
        {{ dynamic_content_for(:key) }}
      </td>
      <td class='val'>
        {{ dynamic_content_for(:val) }}
      </td>
    </tr>
  </table>

<!-- B -->

  <div class='fluid grid'>
    <div class='row'>
      <span class='key width33'>
        {{ dynamic_content_for(:key) }}
      </span>
      <span class='val'>
        {{ dynamic_content_for(:val) }}
      </span>
    </div>
  </div>

teh answerz...
Probably A. It's really a question of semantics, is the data tabular (which would be a good guess for key/value pairs)? Then it goes in a table. Is it something else? Then it goes in a div.
==========================================================
9. which is better?  why?

# A

  if var == 42
    "..."
  end

# B

  if 42 == var
    "..."
  end

teh answerz...
There's a school of thought that putting the unmodifiable value on the LHS prevents acidental assignment. Personally, I don't think it reads well.
==========================================================
10. describe steps to debug this problem

  @response =
    http_request(url, :method => method, :params => params, :headers => headers)

  if @response.ok?
    ship_it!
  else
    debugger!
  end

teh answerz...
Inspect @response for obvious errors. Hit the URL with curl to see what the real world response is.
==========================================================
11. which is better?  why?

# A

  if foo.bar.baz
    '...'
  end

# B

  if foo
    if foo.bar
      if foo.bar.baz
        '...'
      end
    end
  end

teh answerz...
Technically, B is better because it doesn't blow up if foo or bar is nil. However, B is ugly as sin. Null Object Pattern, anyone?
==========================================================
12. is this javascript broken? if so, why?

  ajax(url)({

    'method'  : 'POST',

    'params'  : params,

    'headers' : headers

  });


teh answerz...
Assuming that ajax() returns function, then this is perfectly valid code.
==========================================================
13. what color is this?

  '#FFE'

teh answerz...
"#FFE" -> "#FFFFEE" which is a yellowy off white.
==========================================================
14. what number is this?

  0b101010

teh answerz...
ruby -e 'puts 0b101010'
==========================================================
15. describe an algorithm to detect the 'edges' in these pixels

  0 0 0 0 0 0 
  0 0 1 1 1 0 
  0 1 1 1 1 0 
  0 1 1 1 0 0 
  0 0 0 0 0 0 


teh answerz...
This answer intentionally left blank.
==========================================================
15. what does @X represent?

  $color = [@X, @R, @G, @B].as_hex

 
teh answerz...
Transparency.
==========================================================
16. what are the advantages of static linking?

  export HINT=$LD_RUN_PATH


teh answerz...
The libraries being linked at run time can be changed at any time either by playing with the load path or by out right replacing the files.
==========================================================
17. wtf is this javascript doing?

     var uploader = new qq.FileUploader(options);

     var image_ids = [];

     uploader._uploadFileList = function(){
       image_ids = [];
       var args = Array.prototype.slice.call(arguments);
       var result = qq.FileUploaderBasic.prototype._uploadFileList.apply(uploader, args);
       return(result);
     };


teh answerz...
It overrides uploader._uploadFileList to pre-process the arguments before calling the original function. Think alias_method_chain.
==========================================================
18. what does this code do?

  jQuery('.help').find('a').attr('tabindex', '-1');


teh answerz...
Finds all elements with class "help" then find "a" elements in those results and sets the 'tabindex' attribute to -1 (which make the element not be "keyboard focusable").
==========================================================
19. how would you solve this problem?

  ~ > run_api_tests_locally


    "FAIL: you must access teh API from a box on EC2 with IP 1.2.3.4!"


teh answerz...
Assuming that a) I'm suppost to be hitting the live API and b) I have access to that EC2 instance, I would set up an SSH tunnel from the locally machine to EC2 and talk to the API through it.
If these are suppose to be purely local tests, I'd mock out the API with webmock, fakeweb, vcr, etc.
==========================================================
20. which is better?  why?

// A

  User.prototype.first_name = function(){
    return this.name.split(/\s+/)[0];
  };

// B

  User.prototype.first_name = function(){
    return User.first_name_for(this.name);
  };

  User.first_name_for = function(name){
    return name.split(/\s+/)[0];
  };

teh answerz...
I guess you could argue that B make it easier to override.