JSFiddle - React, Tailwind, and code Playground

JavaScript

function validateIp(ip) {
	if ( ip == null || ip === '' ) {
  	return true;
  }
  
  const parts = ip.split('.');
  if(parts.length !== 4) {
  	return true;
  }
  
  for(let i = 0; i < parts.length; i++) {
  	const part = parseInt(parts[i]);
  	if(part < 0 || part > 255) {
    	return true;
    }
  }
  
  if(ip.endsWith('.')) {
  	return true;
  }
  
  return false;
}

const input = '1.1.1.1,2.2.2.2,3.3.3.,4.4.4.256';
const arr = input.split(',');
const wrongIps = arr.filter(validateIp);


console.log(arr)
console.log(wrongIps)