title: How to enable button when input field is not empty
body: <p>I have a requirement in which there is a form and if all the fields are filled then only submit button will be enabled else the submit button will be in disabled state.</p>
  
  <p><a href="http://jsfiddle.net/M6BzW/576/" rel="nofollow"><strong>This fiddle</strong></a> works fine for 1 input field:</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;button data-bind="enable: my"&gt;My Button&lt;/button&gt;
  &lt;input type="text" name="hi" data-bind="value:my" /&gt;
  </code></pre>
  
  <pre class="lang-js prettyprint-override"><code>ko.applyBindings({ my: ko.observable() });
  </code></pre>
  
  <p>However, I don't know how to do this for <em>multiple</em> input fields like as in <a href="http://jsfiddle.net/M6BzW/577/" rel="nofollow">this fiddle</a>. If there are some 10 input fields then how to enable the submit button if and only if all the fields are filled up.</p>