Javascript 为什么我的代码在使用AJAX时会进入无限循环？

我正在使用这两个函数尝试将客户和订单添加到我的数据库中。我遇到的问题是，我想执行addcustomer，然后执行addOrder，但当我这样尝试时，它进入了一个无限循环

function addCustomer(){
  customer = localStorage.getItem('customer');
  jsonCustomer = JSON.parse(customer);

  var xmlhttp = new XMLHttpRequest();

  if(xmlhttp){
    xmlhttp.onreadystatechange = function(){
      if(xmlhttp.readyState == 4 && xmlhttp.status == 200){
        response = JSON.parse(xmlhttp.responseText);

        customerID = response[0].ID;
        customerFirstName = response[0].FirstName;
        customerSurname = response[0].LastName;
        customerEmail = response[0].Email;
        customerPhoneNumber = response[0].PhoneNumber;
        customerAddress = response[0].Address;
        customerTowm = response[0].Town;
        customerCounty = response[0].County;
        customerPostCode = response[0].PostCode;

        details = "<p>ID: " + customerID + "</p>" + "<p>First Name: " + customerFirstName + "</p>" + "<p>Surname: " + customerSurname + "</p>" + "<p>Email: " + customerEmail + "</p>" + "<p>Phone Number: " + customerPhoneNumber + "</p>" + "<p>Address: " + customerAddress + "</p>" +
                  "<p>Town: " +  + "</p>" + "<p>County: " + customerCounty + "</p>" + "<p>Post Code: " + customerPostCode + "</p>";
        Alert.render("Customer Added", details);

      }
    }
  var url = "addCustomer.php?firstName=" + jsonCustomer.FirstName + "&surname=" + jsonCustomer.Surname + "&email=" + jsonCustomer.Email + "&phoneNumber=" + jsonCustomer.PhoneNumber + "&address=" + jsonCustomer.Address + "&town=" + jsonCustomer.Town + "&county=" + jsonCustomer.County + "&postCode=" + jsonCustomer.PostCode;
  xmlhttp.open("GET", url, false);
  xmlhttp.send();

  addOrder(customerID);

  }
}


function addOrder(customerID){
  customerID = addCustomer();
  var xmlhttp = new XMLHttpRequest();


  if(xmlhttp){
    xmlhttp.onreadystatechange = function(){
      if(xmlhttp.readyState == 4 && xmlhttp.status == 200){
        console.log(xmlhttp.responseText);

        response = JSON.parse(xmlhttp.responseText);

        orderID = response[0].ID;
        orderDate = response[0].Date;
        orderPrice = response[0].TotalPrice;
        orderCustomerID = response[0].Customer_ID;


        details = "<p>ID: " + orderID + "</p>" + "<p>Date: " + orderDate + "</p>" + "<p>Total Price: " + orderPrice + "</p>" + "<p>Customer ID: " + orderCustomerID + "</p>";
        Alert.render("Customer Added", details);


      }
    }

    var url = "../Administration/Checkout/addOrder.php?customerID=" + customerID + "&totalPrice=" + totalPrice;
    xmlhttp.open("GET", url, false);
    xmlhttp.send();

  }
}

函数addCustomer（）{
customer=localStorage.getItem（'customer'）；
jsonCustomer=JSON.parse（customer）；
var xmlhttp=new XMLHttpRequest（）；
if（xmlhttp）{
xmlhttp.onreadystatechange=函数（）{
if（xmlhttp.readyState==4&&xmlhttp.status==200）{
response=JSON.parse（xmlhttp.responseText）；
customerID=响应[0]。ID；
customerFirstName=响应[0]。名字；
customerSurname=响应[0]。姓氏；
customerEmail=响应[0]。电子邮件；
customerPhoneNumber=响应[0]。电话号码；
customerAddress=响应[0]。地址；
customerTowm=响应[0]。城镇；
customerCounty=响应[0]。县；
customerPostCode=响应[0]。邮政编码；
详细信息=“ID:”+customerID+”
“+”名字：“+customerFirstName+”
“+”姓氏：“+customerurname+”
电子邮件：“+customerEmail+”
“+”电话号码：“+customerPhoneNumber+”
“+”地址：“+customerAddress+”
”+
“镇：”++“
县：“+customerCounty+”
“+”邮编：“+customerPostCode+”
”；
警报。呈现（“客户添加”，详细信息）；
}
}
var url=“addCustomer.php？firstName=“+jsonCustomer.firstName+”&姓氏=“+jsonCustomer.姓氏+”&电子邮件=“+jsonCustomer.email+”&电话号码=“+jsonCustomer.phoneNumber+”&地址=“+jsonCustomer.address+”&城镇=“+jsonCustomer.town+”&县=“+jsonCustomer.country+”&邮政编码=“+jsonCustomer.postCode；
open（“GET”，url，false）；
xmlhttp.send（）；
addOrder（customerID）；
}
}
函数addOrder（customerID）{
customerID=addCustomer（）；
var xmlhttp=new XMLHttpRequest（）；
if（xmlhttp）{
xmlhttp.onreadystatechange=函数（）{
if（xmlhttp.readyState==4&&xmlhttp.status==200）{
log（xmlhttp.responseText）；
response=JSON.parse（xmlhttp.responseText）；
orderID=响应[0]。ID；
orderDate=响应[0]。日期；
orderPrice=响应[0]。总价；
orderCustomerID=响应[0]。客户ID；
详细信息=“ID:”+orderID+”
“+”日期：“+orderDate+”
“+”总价：“+orderPrice+”
“+”客户ID:“+orderCustomerID+”
”；
警报。呈现（“客户添加”，详细信息）；
}
}
var url=“../Administration/Checkout/addOrder.php？customerID=“+customerID+”&totalPrice=“+totalPrice；
open（“GET”，url，false）；
xmlhttp.send（）；
}
}

• addCustomer

  将始终在

  addCustomer

  结束前调用

  addOrder

  （除非浏览器不支持

  XMLHttpRequest

  ）

• addOrder

  将始终调用

  addCustomer

  （在其第一行）

---

您需要一个条件来阻止其中一个调用的发生，以避免无限循环。

您有

addCustomer（）

调用

addOrder

，它在第一行再次调用

addCustomer

，这就是无限调用的原因

function addCustomer(){
  customer = localStorage.getItem('customer');
  jsonCustomer = JSON.parse(customer);

  var xmlhttp = new XMLHttpRequest();

  if(xmlhttp){
    xmlhttp.onreadystatechange = function(){
      if(xmlhttp.readyState == 4 && xmlhttp.status == 200){
        response = JSON.parse(xmlhttp.responseText);

        customerID = response[0].ID;
        customerFirstName = response[0].FirstName;
        customerSurname = response[0].LastName;
        customerEmail = response[0].Email;
        customerPhoneNumber = response[0].PhoneNumber;
        customerAddress = response[0].Address;
        customerTowm = response[0].Town;
        customerCounty = response[0].County;
        customerPostCode = response[0].PostCode;

        details = "<p>ID: " + customerID + "</p>" + "<p>First Name: " + customerFirstName + "</p>" + "<p>Surname: " + customerSurname + "</p>" + "<p>Email: " + customerEmail + "</p>" + "<p>Phone Number: " + customerPhoneNumber + "</p>" + "<p>Address: " + customerAddress + "</p>" +
                  "<p>Town: " +  + "</p>" + "<p>County: " + customerCounty + "</p>" + "<p>Post Code: " + customerPostCode + "</p>";
        Alert.render("Customer Added", details);

      }
    }
  var url = "addCustomer.php?firstName=" + jsonCustomer.FirstName + "&surname=" + jsonCustomer.Surname + "&email=" + jsonCustomer.Email + "&phoneNumber=" + jsonCustomer.PhoneNumber + "&address=" + jsonCustomer.Address + "&town=" + jsonCustomer.Town + "&county=" + jsonCustomer.County + "&postCode=" + jsonCustomer.PostCode;
  xmlhttp.open("GET", url, false);
  xmlhttp.send();

  addOrder(customerID);

  }
}


function addOrder(customerID){
  customerID = addCustomer();
  var xmlhttp = new XMLHttpRequest();


  if(xmlhttp){
    xmlhttp.onreadystatechange = function(){
      if(xmlhttp.readyState == 4 && xmlhttp.status == 200){
        console.log(xmlhttp.responseText);

        response = JSON.parse(xmlhttp.responseText);

        orderID = response[0].ID;
        orderDate = response[0].Date;
        orderPrice = response[0].TotalPrice;
        orderCustomerID = response[0].Customer_ID;


        details = "<p>ID: " + orderID + "</p>" + "<p>Date: " + orderDate + "</p>" + "<p>Total Price: " + orderPrice + "</p>" + "<p>Customer ID: " + orderCustomerID + "</p>";
        Alert.render("Customer Added", details);


      }
    }

    var url = "../Administration/Checkout/addOrder.php?customerID=" + customerID + "&totalPrice=" + totalPrice;
    xmlhttp.open("GET", url, false);
    xmlhttp.send();

  }
}

由于

addOrder

方法需要

addCustomer

ajax调用返回的

customerId

，因此您需要在

addCustomer

的成功中调用

addOrder

方法，并可以将

customerId

作为pram传递给

addOrder

方法

function addCustomer() {
    customer = localStorage.getItem('customer');
    jsonCustomer = JSON.parse(customer);

    var xmlhttp = new XMLHttpRequest();

    if (xmlhttp) {
        xmlhttp.onreadystatechange = function () {
            if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
                var response = JSON.parse(xmlhttp.responseText);

                customerID = response[0].ID;
                customerFirstName = response[0].FirstName;
                customerSurname = response[0].LastName;
                customerEmail = response[0].Email;
                customerPhoneNumber = response[0].PhoneNumber;
                customerAddress = response[0].Address;
                customerTowm = response[0].Town;
                customerCounty = response[0].County;
                customerPostCode = response[0].PostCode;

                details = "<p>ID: " + customerID + "</p>" + "<p>First Name: " + customerFirstName + "</p>" + "<p>Surname: " + customerSurname + "</p>" + "<p>Email: " + customerEmail + "</p>" + "<p>Phone Number: " + customerPhoneNumber + "</p>" + "<p>Address: " + customerAddress + "</p>" +
                    "<p>Town: " + +"</p>" + "<p>County: " + customerCounty + "</p>" + "<p>Post Code: " + customerPostCode + "</p>";
                Alert.render("Customer Added", details);

                //need to call it after the addCustomer is finished
                addOrder(customerID);

            }
        }
        var url = "addCustomer.php?firstName=" + jsonCustomer.FirstName + "&surname=" + jsonCustomer.Surname + "&email=" + jsonCustomer.Email + "&phoneNumber=" + jsonCustomer.PhoneNumber + "&address=" + jsonCustomer.Address + "&town=" + jsonCustomer.Town + "&county=" + jsonCustomer.County + "&postCode=" + jsonCustomer.PostCode;
        xmlhttp.open("GET", url, false);
        xmlhttp.send();
    }
}


function addOrder(customerID) {
    var xmlhttp = new XMLHttpRequest();


    if (xmlhttp) {
        xmlhttp.onreadystatechange = function () {
            if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
                console.log(xmlhttp.responseText);

                response = JSON.parse(xmlhttp.responseText);

                orderID = response[0].ID;
                orderDate = response[0].Date;
                orderPrice = response[0].TotalPrice;
                orderCustomerID = response[0].Customer_ID;


                details = "<p>ID: " + orderID + "</p>" + "<p>Date: " + orderDate + "</p>" + "<p>Total Price: " + orderPrice + "</p>" + "<p>Customer ID: " + orderCustomerID + "</p>";
                Alert.render("Customer Added", details);


            }
        }

        var url = "../Administration/Checkout/addOrder.php?customerID=" + customerID + "&totalPrice=" + totalPrice;
        xmlhttp.open("GET", url, false);
        xmlhttp.send();

    }
}

函数addCustomer（）{
customer=localStorage.getItem（'customer'）；
jsonCustomer=JSON.parse（customer）；
var xmlhttp=new XMLHttpRequest（）；
if（xmlhttp）{
xmlhttp.onreadystatechange=函数（）{
if（xmlhttp.readyState==4&&xmlhttp.status==200）{
var response=JSON.parse（xmlhttp.responseText）；
customerID=响应[0]。ID；
customerFirstName=响应[0]。名字；
customerSurname=响应[0]。姓氏；
customerEmail=响应[0]。电子邮件；
customerPhoneNumber=响应[0]。电话号码；
customerAddress=响应[0]。地址；
customerTowm=响应[0]。城镇；
customerCounty=响应[0]。县；
customerPostCode=响应[0]。邮政编码；
详细信息=“ID:”+customerID+”
“+”名字：“+customerFirstName+”
“+”姓氏：“+customerurname+”
电子邮件：“+customerEmail+”
“+”电话号码：“+customerPhoneNumber+”
“+”地址：“+customerAddress+”
”+
“镇：”++“
县：“+customerCounty+”
“+”邮编：“+customerPostCode+”
”；
警报。呈现（“客户添加”，详细信息）；
//需要在addCustomer完成后调用它
addOrder（customerID）；
}
}
var url=“addCustomer.php？firstName=“+jsonCustomer.firstName+”&姓氏=“+jsonCustomer.姓氏+”&电子邮件=“+jsonCustomer.email+”&电话号码=“+jsonCustomer.phoneNumber+”&地址=“+jsonCustomer.address+”&城镇=“+jsonCustomer.town+”&县=“+jsonCustomer.country+”&邮政编码=“+jsonCustomer.postCode；
open（“GET”，url，false）；
xmlhttp.send（）；
}
}
函数addOrder（customerID）{
var xmlhttp=new XMLHttpRequest（）；
if（xmlhttp）{
xmlhttp.onreadystatechange=函数（）{
if（xmlhttp.readyState==4&&xmlhttp.status==200）{
log（xmlhttp.responseText）；
response=JSON.parse（xmlhttp.responseText）；
orderID=响应[0]。ID；
orderDate=响应[0]。日期；