res.redirect not working as expected

.gitignore

node_modules

_README.md

res.redirect does not support mount point as documented

The use case

Main app calls app.use('/mountpath', otherApp), then all redirects and locations in otherApp must be prefixed with /mountpath. As stated in documentation it's supposed to be supported right out of the box.

What the doc says

Extract from documentation:

This next redirect is relative to the mount point of the application. For example, if you have a blog application mounted at /blog, ideally it has no knowledge of where it was mounted. So, where a redirect of /admin/post/new would simply give you http://example.com/admin/post/new, the following mount-relative redirect would give you http://example.com/blog/admin/post/new:

res.redirect('admin/post/new');

What I do

app.use('/mountpath', otherApp);

otherApp.get('/url', function (req, res) {
  res.redirect('otherUrl');
});

What I expect

http://app/mountpath/url → Location: /mountpath/otherUrl

What I get

http://app/mountpath/url → Location: otherUrl

The demo

Run node server.js and curl http://localhost:3002/mounted/hello and see how you're redirected to world instead of /mounted/world.

_screenshot.png

app.js

var express = require('express');

var app = module.exports = express();

var mountedApp = require('./mounted-app');

app.use('/mounted', mountedApp);

mounted-app.js

var express = require('express');

var app = module.exports = express();

app.get('/hello', function (req, res) {
  res.redirect('world');
});

app.get('/world', function (req, res) {
  res.status(200).json({
    "hello": "world"
  });
});

package.json

{
  "name": "test-express-redirect-mountpath",
  "version": "1.0.0",
  "description": "",
  "main": "mounted-app.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "https://gist.github.com/f6a2903d72d495db6ab7.git"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "express": "^4.8.8"
  }
}

server.js

require('http').createServer(require('./app')).listen(3002).on('listening', function () {
  console.log(this.address());
});