问题描述
localStorage.setItem('auth-token','');
这一行是发生可疑错误的地方。我已经阅读了收到此错误的其他问题，我将在下面发布这些问题。我经常在需要异步或等待的地方看到它，但我很想念它。
这是完整的错误。
(node:2211) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at ServerResponse.setHeader (_http_outgoing.js:547:11)
at ServerResponse.header (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/response.js:771:10)
at ServerResponse.send (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/response.js:170:12)
at ServerResponse.json (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/response.js:267:15)
at checkToken (/Users/devintripp/Desktop/unt-library-system/server/controllers/user-ctrl.js:132:32)
at Layer.handle [as handle_request] (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/layer.js:95:5)
at next (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/route.js:137:13)
at Route.dispatch (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/layer.js:95:5)
at /Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/index.js:281:22
at Function.process_params (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/index.js:335:12)
at next (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/index.js:275:10)
at Function.handle (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/index.js:174:3)
at router (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/index.js:47:12)
at Layer.handle [as handle_request] (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/layer.js:95:5)
at trim_prefix (/Users/devintripp/Desktop/unt-library-system/server/node_modules/express/lib/router/index.js:317:13)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:2211) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block,or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection,use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:2211) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future,promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
我已经把它归结为这段代码。
import React,{ useState,useEffect } from 'react';
import { BrowserRouter,Route,Switch } from 'react-router-dom';
import Axios from 'axios';
import { NavBar } from './components';
import SignIn from './components/auth/SignIn';
import Register from './components/auth/Register';
import { BooksList,BooksInsert,BooksUpdate } from './pages';
import UserContext from './context/UserContext'
import 'bootstrap/dist/css/bootstrap.min.css'
function App() {
//global state for the app to use
const [userData,setUserData] = useState({
token: undefined,user: undefined
})
useEffect( () => {
const checkLoggedIn = async () => {
let token = localStorage.getItem('auth-token');
console.log(token); // this prints "" to the console in the browser
localStorage.setItem('auth-token',''); //this code never changes the headers in chrome
if(token === null || token === ""){
localStorage.setItem('auth-token','');
token = "";
}
const tokenResponse = await Axios.post("http://localhost:8174/user/checkToken",null,{headers: {"x-auth-token": token}});
if(tokenResponse.data){
const userRes = await Axios.get("http://localhost:8174/user/",{headers: {"x-auth-token": token}})
setUserData({token,user: userRes.data})
}
}
checkLoggedIn();
},[]);
return (
<div></div>
);
}
还有一点需要注意的是 localStorage.setItem() 没有将任何标题设置为“”。它根本没有设置标题。
我已经阅读了这个问题： Error: Can't set headers after they are sent to the client
我不在身体或完成状态，也没有在任何地方调用 res.writeHead()。我可以将我的后端调用发布到 /checkToken 和 / 如果这有帮助。
这是我的 checkToken 和 get/calls
checkToken = async (req,res) => {
try {
const token = req.header("x-auth-token")
if(!token){
res.json(false);
}
const verified = jwt.verify(token,process.env.JWT_SECRET);
if(!verified){
return res.json(false);
}
const user = await User.findById(verified.id);
if(!user){
return res.json(false)
}
return res.json(true)
} catch (err) {
return res.status(500).json({msg: err.message});
}
}
getUser = async (req,res) => {
const user = await User.findById(req.user);
// console.log(user)
if(!user){
console.log("no user found")
res.json({msg: "user not found"})
}
res.json({
name: user.name,id: user._id
})
}
这里是那些被调用的地方。
const express = require("express");
// const userCtrl = require("../controllers/user-ctrl");
const router = express.Router();
const UserCtrl = require("../controllers/user-ctrl");
const auth = require("../middleware/auth");
router.post('/register',UserCtrl.registerUser);
router.post('/login',UserCtrl.loginUser);
router.delete('/delete',auth,UserCtrl.deleteUser);
router.post('/checkToken',UserCtrl.checkToken);
router.get('/',UserCtrl.getUser);
module.exports = router;
最后是我的中间件
const jwt = require('jsonwebtoken');
const auth = (req,res,next) => {
try{
const token = req.header("x-auth-token")
if(!token){
return res.status(401).json({msg: "No authentication token found,auth denied."})
}
const verified = jwt.verify(token,process.env.JWT_SECRET);
if(!verified){
return res.status(401).json({msg: "Token verification failed,auth denied."})
}
req.user = verified.id
// res.end();
next();
} catch (err) {
res.status(500).json({error: err.message});
}
}
module.exports = auth;
下面的答案回答了错误。我没有返回我发送的回复，所以它发送了多个回复并且失败了，就像没有休息一样；在案例结束时。
localStorage 仍然是一个问题，无法在 chrome 中设置。
解决方法
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