title: How to highlight Table TD when clicked?
body: <p>basically I have a table grid like the one below, just a lot bigger.</p>
  
  <pre><code>&lt;table&gt;
  &lt;tr&gt;
  &lt;td&gt;&lt;/td&gt;
  &lt;td&gt;&lt;/td&gt;
  &lt;/tr&gt;
  &lt;tr&gt;
  &lt;td&gt;&lt;/td&gt;
  &lt;td&gt;&lt;/td&gt;
  &lt;/tr&gt;
  &lt;/table&gt;
  </code></pre>
  
  <p>And iv used CSS to make then all squares which are 60px by 60px, they wont contain any data but I want to be able to click on the individual squares so that the background color changes and if I click again it goes back to the origional background color. But I want to be able to highlight as many squares as I want.
  I know it would be in JavaScript, but how would I do this?</p>