Javascript - how to pass value into javascript code

Question

I have been having a lot of trouble trying to get value into javascript and pass it to alert. Here is the code that I use to pass the value....

        <img onclick="handpost()" id="colorface" name="red" src="http://www.asl-ela.org/image/redface.png" alt="Red face" /></a>

Then I use function to get the data from img tag....

<script type="text/javascript">
   function handpost()  {
      var color = document.getElementById('colorface').name;
      alert(color);
   }
</script>

I keep getting alert box saying undefined. What does that mean?!?!?!

Answer 1

It means exactly what it reads: document.getElementById('colorface').name is undefined. document.getElementById('colorface') may exist but it doesn't have property name. Try document.getElementById('colorface').getAttribute('name').
name is not standard attribute of img but if you add it then you can access it.