title: Meteor - update var on select change
body: <p>I've got a dropdown, but when a user select another value, I want some code to be executed. My question: How can I check whether the selected value of the dropdown has changed? </p>
  
  <p>In my html file:</p>
  
  <pre><code>&lt;template name="jaren"&gt;    
      &lt;form id="yearFilter"&gt;
          &lt;select class="selectpicker span2" id="yearpicker" &gt;
              {{#each jaren}}
                  {{#if selectedYear}}
                  &lt;option selected value="{{_id}}"&gt;{{jaar}} {{description}}&lt;/option&gt;
                  {{else}}
                  &lt;option value="{{_id}}"&gt;{{jaar}} {{description}}&lt;/option&gt;
                  {{/if}}
              {{/each}}
          &lt;/select&gt; 
      &lt;/form&gt;
  &lt;/template&gt;
  </code></pre>
  
  <p>in my javascript file:</p>
  
  <pre><code>Template.jaren.jaren = function() {
    return Years.find();
  }
  Template.jaren.selectedYear = function() {
    if (Session.get('year_id') == this._id) {
      return true;
    } else {
      return false;
    }
  }
  Template.jaren.events({
    'change form#yearFilter #yearpicker': function(event, template) {
      Session.set('year_id', template.find('#yearpicker').value);
      console.log("value changed");
    }
  });
  </code></pre>