Node.js + Express: What do I have to serve the specific folder's path to express.static?

I wrote the following code:

var express = require('express');
var app = express();

app.use('/', express.static(__dirname ));

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


app.listen(3000, function() {
  console.log("Listening on port 3000");
});

which doesn't work. When open the browser and go to "localhost:3000" I get the error:

path must be absolute or specify root to res.sendFile

Of course the once I fix the line that starts with "app.use..." to:

app.use('/', express.static(__dirname + "./dist"));

then everything works right.

Can you please explain why? What's wrong with giving "express.static" a path of a parent folder of the direct folder of the file sent?

via CrazySynthax