pwgen-reloaded/src/popup/pwgen.js

function randPassword(length, includeSpecial, exclude) {
  let pwdChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
  if (includeSpecial) {
    pwdChars += '!"#$%&\'()*+,-./:;<=>?@[\]^_`{|}~';
  }

  if (exclude) {
    exclude.split('').forEach(c => {
      pwdChars = pwdChars.split(c).join('');
    });
  }

  let randValues = new Uint32Array(length);
  let randPwd = '';
  window.crypto.getRandomValues(randValues);
  for(i=0; i<length; i++)
  {
    randPwd += pwdChars[randValues[i] % pwdChars.length];
  }
  return randPwd;
}

function generateLength() {
  return Math.floor(Math.random() * (getParams().lengthMax - getParams().lengthMin + 1) + getParams().lengthMin);
}

function getParams() {
  return {
    lengthMin: parseInt(document.getElementById('length-min').value),
    lengthMax: parseInt(document.getElementById('length-max').value),
    special: document.getElementById('special').checked,
    exclude: document.getElementById('exclude').value,
    directcopy: document.getElementById('directcopy').checked
  }
}

function loadOptions() {
  return browser.storage.local.get({
    lengthMin: 14,
    lengthMax: 17,
    special: true,
    exclude: 'iIl|10o8B3Evu![]{}',
    directcopy: false
  });
}

function saveOptions(options) {
  return browser.storage.local.set(options);
}

function copypasstoclippboard(cb) {
  setTimeout(function() {
    var copyText = document.getElementById('pw');
    copyText.select();
    document.execCommand('copy');
    if (typeof(cb) === 'function') {
      cb();
    }
    fade(document.getElementsByClassName('copied')[0]);
  }, 200);
}

function fade(element) {
  var clone = element.cloneNode(true);
  clone.style.display = 'block';
  element.parentNode.insertBefore(clone, element.nextSibling);

  setTimeout(() => {
    clone.className += ' fadeout';
  }, 500);

  setTimeout(() => {
    clone.remove();
  }, 1600);
}

document.addEventListener('DOMContentLoaded', function() {

  document.getElementById('new').addEventListener('click', (ev) => {
    ev.preventDefault();
    var params = getParams();
    document.getElementById('pw').value = randPassword(generateLength(), params.special, params.exclude);
  });

  document.getElementById('copy').addEventListener('click', (ev) => {
    ev.preventDefault();
    copypasstoclippboard();
  });

  var list = document.getElementsByTagName('input');
  for (var i = 0; i < list.length; i++) {
    list[i].addEventListener('change', (ev) => {
      saveOptions(getParams());
    });
  }

  loadOptions().then((options) => {
    document.getElementById('length-min').value = options.lengthMin;
    document.getElementById('length-max').value = options.lengthMax;
    document.getElementById('special').checked = options.special;
    document.getElementById('exclude').value = options.exclude;
    document.getElementById('directcopy').checked = options.directcopy;
    document.getElementById('pw').value = randPassword(generateLength(), getParams().special, getParams().exclude);

    if (options.directcopy) {
      copypasstoclippboard();
    }
  });

});