What is the difference between redirect and next in NodeJs?

Question

I quite don't understand the difference between these two:

app.get('*', function(req, res, next) {
  next();
 //ROUTE 1
});

app.get('*', function(req, res) {
  res.redirect('/some');
  //ROUTE 2
});

app.get('/some', function(req, res) {
  res.send("success");
  //ROUTE 3
});

When I try making request to ROUTE 1, I get response success but ROUTE 2 doesn't show this response. Why is that?

What I want to do is:

Every request should pass from ROUTE 1 and the control should be handled to a SPECIFIC route, which I would write in it ROUTE if-else statement (not like next(), which sends control to next MATCHING route).

For example:

app.get('*', function(req, res, next) {
  if(x==y){
    //call SPECIFIC route 3 
  } else {
    // call SPECIFIC route 4 (another route)
    //ROUTE 1
});

I tried to do it with redirect but it's not working.

Thank you.

EDIT:

• Routes would be: /checkIfSession exists. I would use express-session to check if user's username exists or not in session.

If exists, I want to send control to if otherwise else.

Assume the requests are:

1. http://198.168.43.200:3000/checkIfSession

2. http://198.168.43.200:3000/some

(I will call only 1st request).

EDIT 2: I tried following but I don't get any response when I request:

app.use(function (req, res, next) {
    if(2==2){
        res.redirect("/session");
    } else {
        res.end("else");
   }
});

app.get("/session", function(req, res){
    res.write("session");
    res.end();
});

app.get("/some", function(req, res){
    res.write("some");
    res.end();
});

Request: /some

Answer 1

I suppose if you want your routes to go through some kind of authentication first you can use middleware in your routes.

Below is sample code:

app.get('/some', checkSession, function(req, res) {
  res.send("success");
});

// this is the middleware function

function checkSession(req, res, next) {
    // do your checking here
    if (x===y) {
        next();
        //continue users access to protected API
    } 
    else {
        res.redirect('/');
        // redirect user to the default login page
    }
} 

In this above example there are 2 Cases

Case1:

x === y as from your given example I'am assuming users is logged in, so when the user is accessing /some section of your website he will receive Success from the server.

This is the use of your next() function i.e. it continues the execution of that api or sends the data whatever the user is requesting. Something similar to continue in your programming.

Case2:

x!==y now this will be the case where user is not authenticated or logged in and user is still trying to access the /some section of your website. In this case user will be redirected to login page of whatever you have designed for your website for him/her to re-enter his/her credentials.

Here your redirect function redirects the user without sending any data. Something similar to the break.