Detecting if a SalesOrder can be billed

Hello NetSuite Community!

I'm trying to write a SuiteScript that determines if a SalesOrder can be billed or not. I'd love a quick set of eyes on the script to see if I've forgotten about any details. Thanks in advance!

 function canSalesOrderBeBilled(salesOrderId) {    var salesOrderStatus = nlapiLookupField('salesorder', salesOrderId, 'statusRef');      if(salesOrderStatus == 'pendingBilling' || salesOrderStatus == 'pendingBillingPartFulfilled' || salesOrderStatus == 'pendingApproval') {      return true;    }      if(salesOrderStatus == 'billed' || salesOrderStatus == 'closed' || salesOrderStatus == 'cancelled') {      return false;    }      var filters = [      new nlobjSearchFilter('createdfrom', null, 'anyof', salesOrderId)    ];      var invoiceResults = nlapiSearchRecord(      'invoice',      null,      filters,      null    );      var salesOrderResults = nlapiSearchRecord(      'cashsale',      null,      filters,      null    );      if(invoiceResults || salesOrderResults) {      return false;    }      return true;  }