app.js

'use strict';

let GithubGraphQLApi = require('node-github-graphql');

let github = new GithubGraphQLApi({
    token: '<your token here>'
});

module.exports.hello = (event, context, callback) => {
  github.query(`
  {
    repository(owner: "laravel", name: "blog-contest-may-mayhem") {
      issues(first: 100, states: OPEN) {
        nodes {
          title
          reactions(first: 100, content: THUMBS_UP) {
            totalCount
            nodes {
              user {
                company
                location
                createdAt
              }
            }
          }
        }
      }
    }
  }
  `, null, (res, err) => {
    let issues = res.data.repository.issues.nodes.map((issue) => {
      return {
        title: issue.title,
        votes: issue.reactions.totalCount,
        voters: issue.reactions.nodes.map(user => user.user),
      };
    });
    issues.sort((a, b) => {
      if (a.votes < b.votes) return -1;
      if (a.votes > b.votes) return 1;
      return 0;
    });
    issues.reverse();

    let output = '';
    let position = 1;
    for (let issue of issues) {
      // Locations
      let locations = issue.voters.map(voter => voter.location);
      locations = locations.filter(location => location !== null);
      // Split locations on `,` and `-` and `/`
      locations = locations.map(location => location.split(/[-,\/]+/).slice(-1)[0].trim());
      // Lowercase
      locations = locations.map(location => location.toLowerCase());
      // Cities to countries
      locations = locations.map(location => {
        const cities = {
          'antwerp': 'belgium',
          'amsterdam': 'netherlands',
          'the netherlands': 'netherlands',
          'rotterdam': 'netherlands',
          'nederland': 'netherlands',
          'the hague': 'netherlands',
          'pune': 'india',
          'vadodara': 'india',
          'dublin': 'ireland',
          'copenhagen': 'denmark',
          'nairobi kenya': 'kenya',
          'brasil': 'brazil',
          'kerala': 'india',
          'ahmedabad': 'india',
          'chandigarh': 'india',
          'berlin': 'germany',
          'paris': 'france',
          'lyon': 'france',
          'strasbourg': 'france',
          'beijing china': 'china',
          'new dametta_dametta': 'egypt',
          'damitta': 'egypt',
          'mahalla': 'egypt',
          'esfahan': 'iran',
          'baharestan': 'iran',
          'chennai': 'india',
          'rajkot': 'india',
          'gurgaon': 'india',
          'mons': 'belgium',
          'kraków': 'poland',
          'krakow': 'poland',
          'cracow': 'poland',
          'mielec': 'poland',
          'deutschland': 'germany',
          'zurich': 'switzerland',
          'tirana': 'albania',
          'shanghai.jiangsu.china': 'china',
          'wuxi jiangsu': 'china',
          'mons': 'belgium',
          'kuala lumpur': 'malaysia',
          'jakarta': 'indonesia',
          'united states': 'usa',
          'san diego': 'usa',
          'arizona': 'usa',
          'phoenix': 'usa',
          'california': 'usa',
          'az': 'usa',
          'mi': 'usa',
          'mx': 'usa',
          'wa': 'usa',
          'nc': 'usa',
          'il': 'usa',
          'tx': 'usa',
          'sydney': 'australia',
          'sydney australia': 'australia',
          'london': 'uk',
          'united kingdom': 'uk',
          'aberdeen': 'uk',
          'essex': 'uk',
        };
        if (location in cities) {
          return cities[location];
        }
        return location;
      });
      // Count and sort
      var locationsCount = {};
      locations.forEach(function(i) { locationsCount[i] = (locationsCount[i]||0) + 1;});
      var sortedLocations = [];
      for (let location in locationsCount) {
          sortedLocations.push([location, locationsCount[location]]);
      }
      sortedLocations.sort(function(a, b) {
          return b[1] - a[1];
      });

      // Creation date
      let creationDates = issue.voters.map(voter => new Date(voter.createdAt));
      creationDates = creationDates.filter(date => date >= new Date('2018-05-22'));

      output += '#' + position + ' - ';
      position++;
      output += issue.votes;
      output += ' - ' + issue.title + "\n";

      if (sortedLocations.length > 0) {
        output += "\t";
        for (let location of sortedLocations) {
          output += location[0] + ' (' + location[1] + '), ';
        }
        output += "\n";
      }
      if (creationDates.length > 0) {
        output += "\t" + creationDates.length + ' accounts created after May 22nd: ';
        for (let date of creationDates) {
          output += date.toISOString().slice(0, 10) + ', ';
        }
        output += "\n";
      }
      output += "\n";
    }

    callback(null, {
        statusCode: 200,
        body: output,
    });
  });
};

Your example link at https://github.com/laravel/blog-contest-may-mayhem/issues/57 returns the wrong content type, application/json instead of text/plain 🤔