tail-stream-pipe-http-server.js

var ts = require('tail-stream');
require('http').createServer(function (req, res) {
    res.writeHead(200, {
        'Content-Type': 'text/plain'
    });
    var stream = ts.createReadStream(req.url.substr(1), {
        detectTruncate: true,
        onTruncate: 'end',
        endOnError: false
    });
    stream.pipe(res);
}).listen(8000);

save above file as app.js
$ curl http://localhost:8000/app.js to see
$ echo "//test" >> app.js