How to use express response to stay in the same page without redirect?

Question

Consider a simple form which takes email as input. Submit button calls a bootstrap modal in case authentication failed. If at success, it redirects to the next view.

When bootstrap modal appears, the browser is constantly loading the page, waiting a response.

I am using this code on server side:

app.post('/', (req, res) => {
    Users.findOne({
        email: req.body.email
    })
    .then(user => {
        if (user) {
            obj = req.body.email
            res.redirect('/survey')
        }
    })
})

I tried to add an else statement in case user is not found:

...
else  {
  console.log('User not found')
  return
}

I do not want to redirect to the same page because modal will not work.

Is there a res method in order to achieve this?

Answer 1

The proper solution will be to use ajax for submitting form data & handling response

based on the response success / failure, you can redirect user or show modal for error from client side

If you still want to do it without ajax submission of form, you can redirect user to same url with adding querystring

res.redirect('/same-path?error=user_not_found') 

And check query params on load of page in client javascript

$(document).ready ( function(){
    var url = window.location.search;
    var queryStr = url.split("?")[1];

    if(queryStr) {
        let hash = queryStr.split('&);
        for (var i = 0; i < hash.length; i++) {
            params=hash[i].split("=");
            if(params[0] == 'error' && params[1] == 'user_not_found') {
                // SHOW YOUR MODAL HERE
            }
        }
    }
});​