Nov 12, 2010 06:50 PM|jiveabillion|LINK
Using the onKeyUp Event of the Textbox itemPlotSummary we are passing (this) [Is this the control name?]
(this) is a reference to the input element itself. No need to do getElementById(). You can use this function as is
// the only thing you might need to change is RemainingCharacters. You just need to use the client ID of the element in which you wish to display the count.
document.getElementById('RemainingCharacters').innerHTML = textSource.value.length.toString();