when adding filename to file remove last character

I am using this script to add filename as a layer. How to I get it to leave off the last chacter of file

example my file is called L10100-1A and want the added layer filename to be L1100-1

if ( documents.length > 0 )
{
var originalDialogMode = app.displayDialogs;
app.displayDialogs = DialogModes.ERROR;
var originalRulerUnits = preferences.rulerUnits;
preferences.rulerUnits = Units.PIXELS;

try
{
var docRef = activeDocument;

// Now create a text layer at the front
var myLayerRef = docRef.artLayers.add();
myLayerRef.kind = LayerKind.TEXT;
myLayerRef.name = "Filename";

var myTextRef = myLayerRef.textItem;

// strip the extension off
var fileNameNoExtension = docRef.name;
fileNameNoExtension = fileNameNoExtension.split( "." );
if ( fileNameNoExtension.length > 1 ) {
fileNameNoExtension.length--;
}
fileNameNoExtension = fileNameNoExtension.join(".");

myTextRef.contents = fileNameNoExtension;

// off set the text to be in the middle
myTextRef.position = new Array( docRef.width / 2, docRef.height / 2 );
myTextRef.size = 20;
}
catch( e )
{
// An error occurred. Restore ruler units, then propagate the error back
// to the user
preferences.rulerUnits = originalRulerUnits;
app.displayDialogs = originalDialogMode;
throw e;
}

// Everything went Ok. Restore ruler units
preferences.rulerUnits = originalRulerUnits;
app.displayDialogs = originalDialogMode;
}
else
{
alert( "You must have a document open to add the filename!" );