Present index.html no matter the location

I have a express app running on a node and would like the index.html to be presented to the client no matter the url location.

Example: http://example.com

should present the same page as: http://example.com/test

Current code:

var express = require('express');
var app = express();
var server = require('http').Server(app);
var path = require('path');
var port = process.env.PORT || 8000

app.use(express.static(path.join(__dirname, 'public')));

server.listen(port);

app.get('/', function (req, res) {
  res.sendFile(__dirname + '/index.html');
});