custom-shorten-snippet.js

// GET route for custom URLs
app.get('/custom', (req, res) => {
  // sanitize input
  if (typeof (req.query.longUrl) !== "string" ||
      typeof (req.query.customUrl) !== "string") {
    res.send({"shortened": null});
    return;
  }

  let longUrl = qualify(req.query.longUrl);
  let customUrl = req.query.customUrl;

  if (customWordUnavailable(longUrl, customUrl)) {
    res.send({"shortened": null});
  } else {
    customUrl = createCustomMapping(longUrl, customUrl);
    res.send({"shortened": customUrl});
  }
});