How can I link these two object with javascript?

I have some areas of an imagemap and some checkboxes. Each area has a corresponding checkbox, how can I make it so when an area is clicked the corresponding checkbox gets ticked?

Imagemap:

  <%= image_tag("maps/mainmap.png", :width => "450", :height => "450", :class => "map", :usemap => "#mainmap", :alt => "") %>

  <map name="mainmap">
    <area id="area-42" shape="poly" 
      coords="158,43,152,49,164,86,165,112,153,153,139,169,145,171,161,176,236,201,241,202,251,166,253,142,257,132,294,102,269,85,240,68,227,53,213,28,202,27" alt="North"
      data-maphilight='{"stroke":false,"fillColor":"5F9EA0","fillOpacity":0.6}'
      onmouseover="document.body.style.cursor='pointer'" 
      onmouseout="document.body.style.cursor='default'" >

    <area id="area-43" shape="poly" 
      coords="296,103,258,133,254,143,252,166,242,203,263,209,272,204,322,226,340,250,360,241,356,230,357,222,378,214,395,195,394,188" alt=""
      data-maphilight='{"stroke":false,"fillColor":"5F9EA0","fillOpacity":0.6}'
      onmouseover="document.body.style.cursor='pointer'" 
      onmouseout="document.body.style.cursor='default'" >    
  </map>

Checkboxes:

<fieldset class="filter_form_fieldset areas">
  <% Area.all.each do |a| %>
    <p class="area_check"><%= check_box_tag 'areas[]', a.id, false, :id => "area-#{a.id}" %>
    <label for="area-<%= a.id %>"><p1><%= a.name %></p1></label></p>
  <% end %>
</fieldset>

This produces this:

  <img alt="" class="map" height="450" src="/assets/maps/mainmap.png" usemap="#mainmap" width="450" />

  <map name="mainmap">
    <area id="area-41" shape="poly" 
      coords="158,43,152,49,164,86,165,112,153,153,139,169,145,171,161,176,236,201,241,202,251,166,253,142,257,132,294,102,269,85,240,68,227,53,213,28,202,27" alt="North"
      data-maphilight='{"stroke":false,"fillColor":"5F9EA0","fillOpacity":0.6}'
      onmouseover="document.body.style.cursor='pointer'" 
      onmouseout="document.body.style.cursor='default'" >

    <area id="area-42" shape="poly" 
      coords="296,103,258,133,254,143,252,166,242,203,263,209,272,204,322,226,340,250,360,241,356,230,357,222,378,214,395,195,394,188" alt=""
      data-maphilight='{"stroke":false,"fillColor":"5F9EA0","fillOpacity":0.6}'
      onmouseover="document.body.style.cursor='pointer'" 
      onmouseout="document.body.style.cursor='default'" >    
  </map>

  <fieldset class="filter_form_fieldset areas">
      <p class="area_check"><input id="area-41" name="areas[]" type="checkbox" value="41" />
      <label for="area-41"><p1>Chinatown</p1></label></p>
      <p class="area_check"><input id="area-42" name="areas[]" type="checkbox" value="42" />
      <label for="area-48"><p1>Village</p1></label></p>
  </fieldset>

I thought this bit of javascript might link the two, but it's not working, any ideas as to where I'm going wrong?

  $(function() {
    $('area').click(function(){
      var name = $(this).attr('id');
      var $checkbox = $('[id=' + id + ']');
      $checkbox.attr('checked', !$checkbox.attr('checked'));
    });       
  });

Thanks very much for any help!

Solution

You are using the same id value in the <area> tags and in the checkboxes. That will never work. You also had several errors in how you were getting the $checkbox variable.

I changed the <area> tags to use a data value and changed the code to retrieve that data value and it works now. You can see it in action here: http://jsfiddle.net/jfriend00/ndwjC/.

Since we don't have the actual image, one has to guess where to click to find the hotspots, but when you find one, it toggles a checkbox.

HTML:

  <img alt="" class="map" height="450" src="/assets/maps/mainmap.png" usemap="#mainmap" width="450" />

  <map name="mainmap">
    <area data-areanum="area-41" shape="poly" 
      coords="158,43,152,49,164,86,165,112,153,153,139,169,145,171,161,176,236,201,241,202,251,166,253,142,257,132,294,102,269,85,240,68,227,53,213,28,202,27" alt="North"
      data-maphilight='{"stroke":false,"fillColor":"5F9EA0","fillOpacity":0.6}'
      onmouseover="document.body.style.cursor='pointer'" 
      onmouseout="document.body.style.cursor='default'" >

    <area data-areanum="area-42" shape="poly" 
      coords="296,103,258,133,254,143,252,166,242,203,263,209,272,204,322,226,340,250,360,241,356,230,357,222,378,214,395,195,394,188" alt=""
      data-maphilight='{"stroke":false,"fillColor":"5F9EA0","fillOpacity":0.6}'
      onmouseover="document.body.style.cursor='pointer'" 
      onmouseout="document.body.style.cursor='default'" >    
  </map>

  <fieldset class="filter_form_fieldset areas">
      <p class="area_check"><input id="area-41" name="areas[]" type="checkbox" value="41" />
      <label for="area-41"><p1>Chinatown</p1></label></p>
      <p class="area_check"><input id="area-42" name="areas[]" type="checkbox" value="42" />
      <label for="area-48"><p1>Village</p1></label></p>
  </fieldset>

Javascript:

 $(function() {
    $('area').click(function(){
      var name = $(this).data("areanum");
      var $checkbox = $('#' + name);
      $checkbox.attr('checked', !$checkbox.attr('checked'));
    });       
  });

P.S. If you're using a recent version of jQuery, you should probably use .prop() to change the checkbox rather than .attr().