Unable to send headers to the client in expressjs as they have already been set

After successfully logging in, I am trying to redirect to another page but keep encountering the error message "Cannot set headers after they are sent to the client". I understand that I need to place the res.redirect method somewhere else in my code, but I am struggling to figure out the right placement.

router.get('/login',(req,res)=>{
    res.render('login')
})
router.post('/login',(req,res)=>{
    user.findOne({
        where: {
            userName : req.body.userName
        }
    })
    .then(userInfo=>{
        if(userInfo){
            if(bcrypt.compareSync(req.body.password,userInfo.password)){
                const token = jwt.sign(userInfo.dataValues,process.env.SECRET_KEY,{
                    expiresIn:1440
                })

               res.send(token)
               res.redirect('/home')

            }

            else {
                res.status(400).json({error:'user doesnt exist'})
            }


        }
    }
    )
})

Answer №1

res.redirect is essentially a shortcut for setting the redirect status to 302 and adding a Location header. If you want, you can simplify this by:

res.setHeader('Location', '/home');
res.send(token);

However, consider if res.send(token) is really what you need. It may be more appropriate to include a Set-Cookie header in the response from /login. In that case, you could try:

res.setHeader('Set-Cookie', `token=${token}`);
res.redirect('/home');

Alternatively, perhaps your server shouldn't handle the redirect at all. If you are sending the token back to the client, maybe it should be responsible for setting the token in the document cookie and handling the redirect on the client-side like this:

/* This code runs in the browser after receiving the token, not on the server */

document.cookie = `token=${token}`;
window.location.href = '/home';

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Acquire the <li> element when it is clicked using vanilla JavaScript

Whenever a user enters a value in an input field, my function automatically adds a <li> element to a <ul>. Additionally, the function assigns the attribute ( onclick="doneToggle" ) to the created <li>. function createListElement() { ...

Encountering issues during the automated creation of a Nuxt.js application using an Express server

I am attempting to launch Nuxt programmatically from my Express server, but I encounter errors once the application is compiled and I check my browser console: https://i.stack.imgur.com/MZxHk.png https://i.stack.imgur.com/sfDIF.png This is how my nuxt.c ...

The error message "node Unable to iterate over property 'forEach' because it is undefined" appeared

I am facing an error and unable to find the solution. I believe my code is correct. It is related to a video lesson where I attempt to display popular photos from Instagram using the Instagram API. However, when I try to execute it, I encounter this issue. ...

Requesting JSON data from an API with cross-origin - "You might require a suitable loader to manage this particular file format."

I am currently attempting to retrieve JSON data from the Genius API using Webpack and Axios in a web browser. This involves a Cross-Origin Request, which can sometimes be a bit challenging. Initially, I encountered the following error message: Failed to ...

Make sure to choose the radio button that corresponds to the desired title value, as this will be automatically added to the input text

Visit this link for a live example. <div class='liveExample'> <input type="radio" name="gender" value="Mr." checked>Mr. <input type="radio" name="gender" value="Mrs.">Mrs. <p>First name: <input data-bind=&ap ...

What is the best way to split key and value into separate array objects using JavaScript?

Here's a snippet of code I am working with: let obj = {EdadBeneficiario1: '32', EdadBeneficiario2: '5'} var years = []; let i; for (i= obj;i<=obj;i++) { years.push({ edad_beneficiario : i }) } When I run this code, the output i ...

Vue-Firebase: A guide to linking multiple Firebase services in a single app

I am facing an issue with connecting to two firebases within the same project. In my project, I have two javascript files that connect to each firebase separately, which seems fine. Here is how I import them: import db from '../FireBase' i ...

What is the process of replacing fetch with JavaScript?

Looking to test my React application and mock the backend calls, I made the decision to swap out fetch with a Jest function that returns a static value. The issue I encountered was my inability to override the default fetch behavior. After some research, ...

dealing with errors coming from a child asynchronous callback function

function main(){ try { subCallbackFunction(1,(err,res) =>{ if(err){ throw Error(err); } }) } catch (e) { /// Handling error from subCallbackFunction inside this catch block ////// conso ...

Searching for values using keys in Angular

Currently, I am working on a project using Angular where I need to store information based on specific identifiers. To display this information in the Angular application, I am pulling data for different identifiers and showing it on the screen. At the mo ...

error": "Unable to access undefined properties (reading 'SecretString')

Encountering the error message Cannot read properties of undefined (reading 'SecretString') when utilizing @aws-sdk/client-secrets-manager? It's a sign that you should consider updating your code to accommodate the latest version. ...

Is it possible to use different names for the parameters in a function while still maintaining the same

(Apologies for any language barriers!) It's difficult to articulate my thoughts in English, but here is the code I've written: function calculateAge(yearBorn){ return 2020 - yearBorn; } var johnAge = calculateAge(1990); var janeAge = calcul ...

Can the table be automatically updated on page reload?

My goal is to populate a table using $.ajax(), but the content is not showing up when the page first loads. Is there something missing in my implementation of the $.ajax() function? Here's the HTML structure: <div class="row"> <div clas ...

Verifying the type and quantity of an item

Looking at a piece of code where a specific condition is being checked, I'm curious to know why someone might want to skip this particular condition. var number = /^\d+/; var type = Object.prototype.toString.call(obj); for(var key i ...

Error: The Vue Class-Based module failed to parse due to an unexpected character '@'

When I run the command nmp run serve on my Vue project, I encounter two errors. I am following a tutorial that uses class-based Vue, but I am facing this error with all my imported Vue files. As a newcomer to Vue, I am puzzled as to why this error is occur ...

In JavaScript, is it possible to dynamically alter and showcase the value of a select tag?

My code snippet in the HTML file contains Javascript: <script> $(document).ready(function(){ $("#sub").click(function(){ var user_issue = $("#issue").val(); ...

The Node.js Express error message displays an error in events.js at line 167 wherein an 'error' event is not being handled correctly

It seems like there is a syntax error in the bash_profile file on line 9. When trying to run the server using nodemon, an unexpected end of file error occurs. Nodemon is set to restart at any time and is currently watching for chan ...

The CastError occurred when trying to convert the value "0" (string type) to an ObjectId at the path "_id" for the model "Users" during the findOne operation and other related operations

Recently, I started exploring mongodb and nodejs. Unfortunately, I encountered an error when trying to retrieve a specific user using req.params.id from the database. app.get('/user/:id', (req,res) => { console.log(req.params.id) Users ...

Error - Headers already sent cannot be modified

In my Express app, I have a route that sets a cookie after a session is written to the database. However, when the session is successfully written to the database, the route uses res.render to redirect the user to /login, triggering the "can't set hea ...

Guide to resetting a CSS animation with pure JavaScript

My flexbox contains 4 images, each triggering an animation on hover. However, the animation stops if I hover over the same image again. I have tried various JavaScript solutions found online to restart the animation, but none seem to be working for me. S ...