Calculate network address from ip and mask (fragment of network_ip_tool in cidr repo)

getNetworkAddress.js

 const [host, mask] = ev.target.value.split('/');

  if (host.split('.').length !== 4 || mask === undefined || !mask.length ||isNaN(mask)) {
    console.warn('invalid input')
    return;
  }

  const arrBinHost = host.split('.').map((octet) => {
    const octetArr = Number(octet).toString(2).split('');
    const octetArrLength = octetArr.length
    if (octetArrLength < 8) {
      for (let i = 0; i < 8 - octetArrLength; i += 1) {
        octetArr.unshift('0');
      }
    };
    return octetArr;
  });
  
  
  const binMask = Array(Number(mask) + 1).join('1') + Array(32 - Number(mask) + 1).join('0');
  
  const arrBinMask = binMask.match(/.{1,8}/g).map((octet) => octet.split(''));
  
  const arrBinNet = arrBinMask
    .map((octet, octetIndex) => {
      return octet.map((digit, digitIndex) => 
        Number(digit) === 1 && Number(arrBinHost[octetIndex][digitIndex]) === 1 ? "1" : "0" 
      )
    })
  
  
  const netIP = arrBinNet.map((octet) => parseInt(octet.join(''), 2)).join('.');