How to set a property in express scoped to each request

gistfile1.js

// When setting up your application define what you need using 
// http://expressjs.com/api.html#app.use
// In this case we are creating an instance of 'Bar'
app.use(function( req, res, next ) {
  res.locals.foo = 1;
  next();
});


// Later on in your routes you have access to the instance of 'Bar'
// This saves on having to include the Bar 'class' in each route file etc
app.get( '/', function( req, res ) {
  // res.locals.foo is our instance of 'Bar'
  res.locals.foo++;
  // Is foo always 2 here? or does it keep rising with each request?
  res.send('hello world');
});