Fetch the highest record from an Airtable base called 'Invoices', add 1

setNextInvoiceNumber.js

setNextInvoiceNumber(){
  base('Invoices').select({
    maxRecords: 1,
    sort: [{field: "Number", direction: "desc"}]
  }).firstPage((err, records) => {
    records.forEach((record) => {
      this.invoiceNumber = record.get('Number') + 1
    });
  }, function done(err) {
      if (err) { console.error(err); return; }
  });
}