generate a secure password in javascript

Question

What\'s the quickest way to generate a secure password in javascript?

I want it to contain at least 1 special character, and 2 mixed case. Must be at least 6 characters

Answer 1

I modified @Blender's answer to make it more secure, and also without altering String.prototype.

// Copy-pasted from:
// https://stackoverflow.com/questions/12635652/generate-a-secure-password-in-javascript
// and modified for Auth0.
//
// Auth0 requirements:
// https://auth0.com/docs/connections/database/password-strength
//
// "at least 10 characters including at least 3 of the following 4 types of characters:
// a lower-case letter, an upper-case letter, a number, a special character (such as !@#$%^&*).
// Not more than 2 identical characters in a row (such as 111 is not allowed)".

const specials = '!@#$%^&*()_+{}:"<>?\|[];\',./`~';
const lowercase = 'abcdefghijklmnopqrstuvwxyz';
const uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
const numbers = '0123456789';

const all = specials + lowercase + uppercase + numbers;

export default function generatePassword() {
  let password = '';

  password += pick(password, specials, 1, 3);
  password += pick(password, lowercase, 1, 3);
  password += pick(password, uppercase, 1, 3);
  password += pick(password, all, 10);

  return shuffle(password);
}

function pick(exclusions, string, min, max) {
  var n, chars = '';

  if (max === undefined) {
    n = min;
  } else {
    n = min + Math.floor(Math.random() * (max - min + 1));
  }

  var i = 0;
  while (i < n) {
    const character = string.charAt(Math.floor(Math.random() * string.length));
    if (exclusions.indexOf(character) < 0 && chars.indexOf(character) < 0) {
      chars += character;
      i++;
    }
  }

  return chars;
}

// Credit to @Christoph: http://stackoverflow.com/a/962890/464744
function shuffle(string) {
  var array = string.split('');
  var tmp, current, top = array.length;

  if (top) while (--top) {
    current = Math.floor(Math.random() * (top + 1));
    tmp = array[current];
    array[current] = array[top];
    array[top] = tmp;
  }

  return array.join('');
}