Using For With Line Items and If Statement

Hello everyone,

I need a bit of help here. I am trying to write a client script that runs on save record on a Sales Order that will look through all of the line items to see if any have been marked true(check box field) for a custom field called "Is Virtual." If any of them have been checked, then run the rest of my script. The rest of the script works fine without this initial If statement so this is the last piece to the puzzle. Thanks!

function saverecord(){

var LineItemCount = nlapiGetLineItemCount('item');
nlapiLogExecution('debug', 'Line Item Count', LineItemCount);