title: How to call a knockout method with a parameter in select menu changed?
body: <p>I'm new in Knockout. 
  I have 2 dropdown list. The first one is for states' names that is populated in HTML. 
  The second one is for cities, which will be populated by a method in Knockout.js that have a ajax call to populate the cities list depending on the selected state. This method will be called on change in state dropdown.</p>
  
  <p>I know that we can call a method on change in this way: </p>
  
  <pre><code>&lt;select id="state" name="state" data-bind="event: {change: getCities}"&gt;
  </code></pre>
  
  <p>However, I want to pass the selected state value to the getCities method. How I can do that?</p>
  
  <p>I tried:</p>
  
  <pre><code>&lt;select id="state" name="state" data-bind="event: {change: getCities(this.value)}"&gt;
  </code></pre>
  
  <p>but it does not work. It just pollutes the cities of the default selected menu. The <strong>"this.value"</strong> is send as <strong>undefined</strong>. 
  How I can pass the new selected state value to the method?</p>