title: jquery animation repeated several times
body: <p>I have a problem with the animation. Here is my code:</p>
  
  <pre><code>&lt;html&gt;
      &lt;head&gt;
          &lt;script type='text/javascript' src='http://code.jquery.com/jquery-1.9.1.js'&gt;&lt;/script&gt;
          &lt;title&gt;title&lt;/title&gt;
          &lt;style&gt;
              div{
                  width: 100px;
                  height: 100px;
                  background-color: green;
                  position:relative;
                  left: 0px;
              }
          &lt;/style&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;h1&gt;Animation&lt;/h1&gt;
          &lt;select id='text_1' type="text"&gt;
              &lt;option&gt;100&lt;/option&gt;
              &lt;option&gt;200&lt;/option&gt;
              &lt;option&gt;300&lt;/option&gt;
              &lt;option&gt;400&lt;/option&gt;
              &lt;option&gt;500&lt;/option&gt;
              &lt;option&gt;600&lt;/option&gt;
              &lt;option&gt;700&lt;/option&gt;
              &lt;option&gt;800&lt;/option&gt;
              &lt;option&gt;900&lt;/option&gt;
              &lt;option&gt;1000&lt;/option&gt;
          &lt;/select&gt;
          &lt;button&gt;Animate Div&lt;/button&gt;&lt;br/&gt;&lt;br/&gt;
          &lt;div&gt;&lt;/div&gt;
          &lt;script&gt;
              $(document).ready(function(){
                  var number = 500;
                  $('#text_1').bind('change', function(){
                      var number_2 = $('#text_1').val() != '' ? $('#text_1').val() : 500;
                      animation(number_2);
                  });
                  animation(number);
              });
              function animation(num){
                  $('button').click(function(){
                      $('div').animate({
                          'left': num+'px',
                      }, 1000).animate({
                          'left': '0px',
                      }, 1000);;
                  });
              }
          &lt;/script&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>When I change select option (example: 300) and click the button, then does a two animations.
  when I change select option again, then does a tree animations.
  What is wrong. Please help.</p>