hoe to make password and username validation in javascript code example

Example 1: password and confirm password validation js

var check = function() {
  if (document.getElementById('password').value ==
    document.getElementById('confirm_password').value) {
    document.getElementById('message').style.color = 'green';
    document.getElementById('message').innerHTML = 'matching';
  } else {
    document.getElementById('message').style.color = 'red';
    document.getElementById('message').innerHTML = 'not matching';
  }
}

Example 2: Javascript validate password

let pattern = new RegExp("^(?=(.*[a-zA-Z]){1,})(?=(.*[0-9]){2,}).{8,}$"); //Regex: At least 8 characters with at least 2 numericals
    let inputToListen = document.getElementById('pass-one'); // Get Input where psw is write
    let valide = document.getElementsByClassName('indicator')[0]; //little indicator of validity of psw

    inputToListen.addEventListener('input', function () { // Add event listener on input
        if(pattern.test(inputToListen.value)){
            valide.innerHTML = 'ok';
        }else{
            valide.innerHTML = 'not ok'
        }
    });

Example 3: password validation in javascript

var check = function() {
  if (document.getElementById('password').value ==
    document.getElementById('confirm_password').value) {
    document.getElementById('message').style.color = 'green';
    document.getElementById('message').innerHTML = 'matching';
  } else {
    document.getElementById('message').style.color = 'red';
    document.getElementById('message').innerHTML = 'not matching';
  }
}
let pattern = new RegExp("^(?=(.*[a-zA-Z]){1,})(?=(.*[0-9]){2,}).{8,}$"); //Regex: At least 8 characters with at least 2 numericals
    let inputToListen = document.getElementById('pass-one'); // Get Input where psw is write
    let valide = document.getElementsByClassName('indicator')[0]; //little indicator of validity of psw

    inputToListen.addEventListener('input', function () { // Add event listener on input
        if(pattern.test(inputToListen.value)){
            valide.innerHTML = 'ok';
        }else{
            valide.innerHTML = 'not ok'
        }
    });