title: Why does ng-click not work in case-1, but does in case-3?
body: <p>There is clearly something fundamental im not yet understanding.</p>
  
  <p>Im trying to make user of the Modal module in Angular Ui.Bootstrap but im finding that my clicks are not activating the <code>open()</code> function -- So boiling it down to a very simple testcase, as below, im not seeing any calls when the ng-click points to a function (alert or console.log), but does work when the ng-click points to something which is just an expression </p>
  
  <p>Why is the <code>alert</code> not called in the first example?</p>
  
  <pre><code>&lt;div data-ng-app&gt;
      &lt;button data-ng-click="alert('Message 1');"&gt;
          ngClick -- not working, why not?
      &lt;/button&gt;
      &lt;button onclick="alert('Message 2');"&gt;
          Plain onclick
      &lt;/button&gt;
      &lt;button data-ng-click="count = (count + 1)"&gt;
            But this works, why ???
      &lt;/button&gt;
      count: {{count}}
  &lt;/div&gt;
  </code></pre>
  
  <p><a href="http://jsfiddle.net/H2wft/1/">http://jsfiddle.net/H2wft/1/</a></p>