const fs = require('fs');
const path = require('path');

function showFile(folderName, done) {
    fs.readdir(path.join('./public', folderName), (err, files) => {
        files.some(file => {
            done('http://localhost/public/' + folderName + '/' + file.toString());
        });
    });
}

///

app.get('/:id', (req, res) => {
    showFile(req.params.id, file => {
        res.render('index', {title: req.params.id, img: file});
    });
})