Node.js nodejs response.end重复事件

我正在使用nodejshttp库。我在控制台上看到两个日志。为什么？我取字段

response.end（JSON.stringify（{'asd'：'asd'}））结果：一个日志

var config = require('./config.js');
var http = require('http');
var url = require('url');
var querystring = require('querystring');
var requester = require('request');

var server = http.createServer(function (request, response) {
    response.setHeader('Access-Control-Allow-Origin', config.allowOrgin);
    response.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
    response.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type,X-AUTH-TOKEN,accept,customheader,x-my-custom-header,request_id');
    response.setHeader('Access-Control-Allow-Credentials', true);
    response.writeHead(200, "OK", { 'Content-Type': 'application/json' });

    var urlData = url.parse(request.url, true);
    var requestUrl = config.appUrl + urlData.pathname;
    var formData = querystring.parse(body);

    var body = '';
    request.on('data', function (data) {
        body += data.toString();
    });
    console.log('asd');
    response.end(JSON.stringify(body));
}).listen(config.port, config.host);
console.log(config.host + ':' + config.port);

如果您从web浏览器点击服务器，您将看到两个控制台日志，因为浏览器还向
/favicon.ico
发送请求，以检查您的网站是否提供了要在浏览器选项卡中显示的图标

将控制台日志替换为
console.log（'req.url:'+req.url）以查看