aws_ip_count.js

const subnetMap = { 8: 16777214, 9: 8388606, 10: 4194302, 11: 2097150, 12: 1048574, 13: 524286, 14: 262142, 15: 131070, 16: 65534, 17: 32766, 18: 16382, 19: 8190, 20: 4094, 21: 2046, 22: 1022, 23: 510, 24: 254, 25: 126, 26: 62, 27: 30, 28: 14, 29: 6, 30: 2, 31: 1};

const AWS_IP_RANGE_URL = 'https://ip-ranges.amazonaws.com/ip-ranges.json';
const CORS_URL = 'https://jsonp.afeld.me/?url=' + AWS_IP_RANGE_URL;

function filterUnique(p, c, i) { ~~p.indexOf(c) && p.push(c); return p; };

fetch(CORS_URL)
  .then(function(response) {
    response
      .json()
      .then(function(data) {
        let ipList = data.prefixes
          .map(function(p) { return p.ip_prefix; } )
          .reduce(filterUnique, []);

        let totalIpCount = ipList
          .map(function(ip) { return subnetMap[ip.split('/')[1]]; } )
          .reduce(function(p, c, i) { return p + c; }, 0 );

        console.log('Total count: %s', totalIpCount);
    });
  }
);