Javascript 又一个",；can'；t在发送后设置标题"；

我使用node.js服务器向前端发送响应。当我在MyNodeServer.js代码中添加setHeaders时，出现“发送后无法设置头”错误。我的代码已粘贴在下面

   web server listening to port 8080, started
    _http_outgoing.js:367
        throw new Error('Can\'t set headers after they are sent.');
        ^

    Error: Can't set headers after they are sent.
        at ServerResponse.setHeader (_http_outgoing.js:367:11)
        at ServerResponse.writeHead (_http_server.js:183:21)
        at ...\MyNodeServer.js:71:26
        at FSReqWrap.readFileAfterClose [as oncomplete] (fs.js:416:3)

MyNodeServer.js

var myHttp = require("http");
var url = require("url");
var qString = require("querystring");
var fs = require('fs');

var myEvents = require('./customEvents');

var myAppWebServer = myHttp.createServer(function(request, response){

    response.setHeader('Access-Control-Allow-Origin', 'http://localhost:8080');

    response.setHeader('Access-Control-Allow-Methods',
          'GET, POST, OPTIONS, PUT, PATCH, DELETE');

    response.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
    response.setHeader('Access-Control-Allow-Credentials', true);

    if (request.method === "OPTIONS") {
        return response.status(200).end();
    }

    var query =url.parse(request.url).query;
    response.writeHead(405, {'content-type':'text/html'});
    var yourVisit;
    var pName = url.parse(request.url).pathname;
    if(pName==='/register'){      
       response.end('{ "name":"xxx", "city":"yyy"}');
    }else if (pName==='/login'){
         fs.readFile("pages/login.html", function (error, pgResp) {
            response.writeHead(200, { 'Content-Type': 'text/html' });
            response.write(pgResp);
            response.end();
         });
    } 
});

myAppWebServer.listen(8080);

---

正在多次发送响应。（由于声誉低下，无法发表评论。）

状态代码被写入两次

改变

response.writeHead(405, {'content-type':'text/html'});

到

---

正在多次发送响应。（由于声誉低下，无法发表评论。）

状态代码被写入两次

改变

response.writeHead(405, {'content-type':'text/html'});

到