title: How to count the number of times a DIV is clicked?
body: <p>I wanna to count the number of times a div clicked. For example,</p>
  
  <pre><code>&lt;div id="id1"&gt;
    click here..
  &lt;/div&gt;
  &lt;div id="id2"&gt;
    click here..
  &lt;/div&gt;
  ......
  </code></pre>
  
  <p>I want to click these div one time only. If the user clicks the second time, it will display the error msg. 
  Anyone can help? pls!</p>