local and development

var express = require("express");
var app = express();
app.use(express.static(__dirname + "/app")); 
app.use("/app/bower_components", express.static(__dirname + "/app/bower_components"));
app.use("/app/dist/min/css/fonts/", express.static(__dirname + "/app/dist/min/css/fonts/"));
app.all('/*', function(req, res, next) {
    res.sendFile("/app/index.html", { root: __dirname });
});

app.listen(process.env.PORT || 3000);

production

var express = require("express");
var app = express();
app.use(express.static(__dirname + "/"));
app.all('/*', function(req, res, next) {
    res.sendFile("/index.html", { root: __dirname });
});

app.listen(process.env.PORT || 3000);