You could use the static
middleware:
app.use("/", express.static(__dirname));
A server example:
var express = require('express');
var app = express();
app.use('/', express.static(__dirname + '/public'));
app.listen(3000, function() { console.log('listening')});
This is the file structure:
.
├── public
│ ├── a.html
│ ├── b.html
│ └── c.html
└── server.js
Documentation: