script.js

let sliderElement = document.querySelector('#slider');
let buttonElement = document.querySelector('#button');

let sizePassword = document.querySelector('#valor');
let password = document.querySelector('#password');

let containerPassword = document.querySelector('#container-password');

let charset =
  'ABCDEFGHIJKLMNOPQRSTUVWXYZ!@&*abcdefghijklmnopqrstuvwxyz0123456789';

let newPassword = '';

sizePassword.innerHTML = sliderElement.value;

slider.oninput = function () {
  sizePassword.innerHTML = this.value;
};

function generatePassword() {
  let pass = '';
  for (let i = 0, n = charset.length; i < sliderElement.value; ++i) {
    pass += charset.charAt(Math.floor(Math.random() * n));
  }
  containerPassword.classList.remove('hide');
  password.innerHTML = pass;
  newPassword = pass;
}

function copyPassword() {
  navigator.clipboard.writeText(newPassword);
  alert('Senha copiada com sucesso!');
}