我在node.js中写了这个简单的登录代码：

var express = require ("express");

var badyparser = require ("body-parser");

var app = express();

app.use(express.static(__dirname + "/static"));

app.use(badyparser());

var users = {

tom : "1",

jenny : "12",

mary : "123"

};

app.get("/" , function(req,resp,next){

resp.sendFile(__dirname + "/static/home.html")

});

app.post("/login" , function(req , resp , next){

// console.log(req.body); // print in terminal

// console.log(users);

for (user in users) {

if (req.body['username'] == user){

if (req.body['password'] == users[user]){

resp.json({status : "true" , msg : "YES"});

console.log("YES");

}

else {

resp.json({status : "false" , msg : "password is false"});

console.log("password is false");

}

}

else {

resp.json({status : "false" , msg : "user not found"});

console.log("user not found");

}

}

} );

app.listen(8000);

console.log("port open");

在浏览器页面显示正确答案但在终端显示此错误：

错误：发送后无法设置标头 . 在ServersResponse.header的ServerResponse.setHeader(_http_outgoing.js：501：3)的validateHeader(_http_outgoing.js：494：11)处(/Users/mohammad/Desktop/test/Login/node_modules/express/lib/response.js： 767：10)在ServerResponse.send上的ServerResponse.send(/Users/mohammad/Desktop/test/Login/node_modules/express/lib/response.js:170:12)(/ Users / mohammad / Desktop / test / Login / node_modules / express / lib / response.js：267：15)在/Users/mohammad/Desktop/test/Login/server.js:36:8在Layer.handle [as handle_request](/ Users / mohammad / Desktop / test /Login/node_modules/express/lib/router/layer.js:95:5)下一步(/Users/mohammad/Desktop/test/Login/node_modules/express/lib/router/route.js:137:13)at at在Layer.handle上的Route.dispatch(/Users/mohammad/Desktop/test/Login/node_modules/express/lib/router/route.js:112:3)[as handle_request](/ Users / mohammad / Desktop / test / Login /node_modules/express/lib/router/layer.js:95:5)

(我是节点中的新人)谢谢