Implementing custom javascript effects in IceFaces

Using icefaces you sometimes need some custom JavaScript functionality. A good way to do this is extending the effects machinery.

We are going to implement a scroll effect which will allow to scroll down a textarea on demand as an example.

First of all we are going to create the JavaScript functionality we are going to use:

<script type="text/javascript">
function scrollDown(id) {
   ta=document.getElementById(id);
   ta.scrollTop=ta.scrollHeight;
}
</script>

you may want to use a more elaborated name to avoid name clashing.
Now we are going to create the Java class that would allow us to control the effect from the Java side:

import com.icesoft.faces.context.effects.Effect;

public class ScrollDown extends Effect {

  @Override //This annotation is optional but advisable
  public String getFunctionName() {
    return "scrollDown";
  }
}

Now you can use this Effect as any other in your code. Just remember that the JavaScript function must be present for the effect to work.
Enjoy!