Generate a list of the common-denominator CIDR IP ranges from a list of IPs

get_lowest_ip_ranges.js

function getLowestIpRanges(ips) {
  let ipRanges = [];

  ips.forEach(x => {
    let x3 = x.replace(/\d+$/, '');
    let x2 = x3.replace(/\d+\.?$/, '');
    let x1 = x2.replace(/\d+\.?$/, '');

    let ex = ipRanges.filter(y => y == x3 + '0' || y == x2 + '0.0' || y == x1 + '0.0.0');
    if (ex.length) return;

    ex = ipRanges.filter(y => y.startsWith(x2));
    if (ex.length) {
      ipRanges.splice(ipRanges.indexOf(x[0]), 1)
      ipRanges.push(x2 + '0.0')
    } else {
      ex = ipRanges.filter(y => y.startsWith(x1));
      if (ex.length) {
        ipRanges.splice(ipRanges.indexOf(x[0]), 1)
        ipRanges.push(x1 + '0.0.0')
      } else {
        ipRanges.push(x3 + '0')
      }
    }
  });

  ipRanges = ipRanges.map(x => x.endsWith('.0.0.0') ? (x + '/8') : (x.endsWith('.0.0') ? (x + '/16') : (x + '/24')));

  return ipRanges;
}