index.js

var request = require('request');
var bodyParser = require('body-parser');
var express = require('express');
var url = require('url');
var app = express();

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

app.set('port', (3000 || process.env.PORT));
app.get('/', function(req, res){ res.send('Server running.'); });

// genius endpoint 
app.post('/post', function(req, res){
    var parsed_url = url.format({
        pathname: 'https://api.genius.com/search',
        query: {
            access_token: process.env.GENIUS_ACCESS,
            q: req.body.text
        }
  });

    // giving slack a response
    request(parsed_url, function (error, response, body) {
        if (response.statusCode == 200 && !error) {
            var data = JSON.parse(body);
            var first_url = data.response.hits[0].result.url; // parse URL
            var body = { // pulling out first link from JSON
              response_type: "in_channel",
              text: first_url
            };
            res.send(body); // sends the response
        }
    });
});

//run locally
app.listen(app.get('port'), function() { 
    console.log('Open localhost:', app.get('port'), 'on your browser.'); 
});