function checkProduct() {
  var pcode = document.getElementById("product_code").value;
  var pid = document.getElementById("product_id").value;
  var url = "check_product.php?code=" + pcode + "&id=" +pid;
  request.open("GET", url, true);
  request.onreadystatechange = productValidated;
  request.send(null);
}
function productValidated() {
  if (request.readyState == 4) {
    if (request.status == 200) {
      var productDescription = request.responseText;

      if ( productDescription == 1 ) {
      	document.getElementById("product_code").value = "";
	alert("Duplicate product code. Please re-enter.");
      	document.getElementById("product_code").focus();
      }
    } else {
      var message = request.getResponseHeader("Status");
      if ((message.length == null) || (message.length <= 0)) {
        alert("Error! Request status is " + request.status);
      } else {
        alert(message);
      }
    }
  }
}
function getProduct1() {
  var pcode = document.getElementById("link_product_1").value;
  var url = "get_product.php?code=" + pcode;
  request.open("GET", url, true);
  request.onreadystatechange = updatePage1;
  request.send(null);
}
function updatePage1() {
  if (request.readyState == 4) {
    if (request.status == 200) {
      var productDescription = request.responseText;
      document.getElementById("link_description_1").innerHTML = productDescription;
    } else {
      var message = request.getResponseHeader("Status");
      if ((message.length == null) || (message.length <= 0)) {
        alert("Error! Request status is " + request.status);
      } else {
        alert(message);
      }
    }
  }
}
function getProduct2() {
  var pcode = document.getElementById("link_product_2").value;
  var url = "get_product.php?code=" + pcode;
  request.open("GET", url, true);
  request.onreadystatechange = updatePage2;
  request.send(null);
}

function updatePage2() {
  if (request.readyState == 4) {
    if (request.status == 200) {
      var productDescription = request.responseText;
      document.getElementById("link_description_2").innerHTML = productDescription;
    } else {
      var message = request.getResponseHeader("Status");
      if ((message.length == null) || (message.length <= 0)) {
        alert("Error! Request status is " + request.status);
      } else {
        alert(message);
      }
    }
  }
}
function getProduct3() {
  var pcode = document.getElementById("link_product_3").value;
  var url = "get_product.php?code=" + pcode;
  request.open("GET", url, true);
  request.onreadystatechange = updatePage3;
  request.send(null);
}

function updatePage3() {
  if (request.readyState == 4) {
    if (request.status == 200) {
      var productDescription = request.responseText;
      document.getElementById("link_description_3").innerHTML = productDescription;
    } else {
      var message = request.getResponseHeader("Status");
      if ((message.length == null) || (message.length <= 0)) {
        alert("Error! Request status is " + request.status);
      } else {
        alert(message);
      }
    }
  }
}
function getProduct4() {
  var pcode = document.getElementById("link_product_4").value;
  var url = "get_product.php?code=" + pcode;
  request.open("GET", url, true);
  request.onreadystatechange = updatePage4;
  request.send(null);
}

function updatePage4() {
  if (request.readyState == 4) {
    if (request.status == 200) {
      var productDescription = request.responseText;
      document.getElementById("link_description_4").innerHTML = productDescription;
    } else {
      var message = request.getResponseHeader("Status");
      if ((message.length == null) || (message.length <= 0)) {
        alert("Error! Request status is " + request.status);
      } else {
        alert(message);
      }
    }
  }
}
function getProduct5() {
  var pcode = document.getElementById("link_product_5").value;
  var url = "get_product.php?code=" + pcode;
  request.open("GET", url, true);
  request.onreadystatechange = updatePage5;
  request.send(null);
}

function updatePage5() {
  if (request.readyState == 4) {
    if (request.status == 200) {
      var productDescription = request.responseText;
      document.getElementById("link_description_5").innerHTML = productDescription;
    } else {
      var message = request.getResponseHeader("Status");
      if ((message.length == null) || (message.length <= 0)) {
        alert("Error! Request status is " + request.status);
      } else {
        alert(message);
      }
    }
  }
}