Google Apps Script: adding SpreadSimple order items in a Google Sheet

Code.gs

function doPost(e) {
  const order = JSON.parse(e.postData.contents)

  const sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet()
  
  const orderDate = new Date()

  order.cartItems.forEach(item => {
    const row = [
      orderDate,
      order.orderId,
      order.client.name,
      order.client.email,
      order.client.phone,
      order.client.message,
      item.sku,
      item.title,
      item.price,
      item.quantity,
      item.price * item.quantity
    ]
    sheet.appendRow(row)
  })
  
  return ContentService.createTextOutput('OK')
}