how you can validate joomla default text editor on blur using jQuery?

This is actually the code things i used get text editor.

$editor = & JFactory::getEditor();
$editor->display('description', $this->my_data->description , 550, 400, 60, 20);

Things I want is I wish to show an alert message alongside text editor saying "you cannot leave this blank". I'm able to get it done in form submit but real challenge is how you can get it done on blur.

$js="function validateEditor(){
        var content = ".$editor->getContent('editorName').";
        if(content == '') {
           alert('Fill the description');
           return false;
        }
        return true;                 
    }";
$document =& JFactory::getDocument();
$document->addScriptDeclaration($js);

Add this code inside your tmpl files

and refer to this as javascript on form submit.