Generate strong and unique passwords with customizable options.

passGen.js

const passwordGen = (
  length = 8,
  {
    includeLowercase: inLc = true,
    includeUppercase: inUc = true,
    includeNumbers: inN = true,
    includeSymbols: inS = true,
    numberOfSymbols: nOfS = 1,
    numberOfNumbers: nOfN = 1,
    numberOfUppercase: nOfUc = 1,
    numberOfLowercase: nOfLc = 1,
    numberOfPassword: nOfPass = 1,
  }
) => {
  const password = [];
  const lowercase = 'abcdefghijklmnopqrstuvwxyz';
  const uppercase = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  const numbers = '0123456789';
  const symbols = '!@#$%^&*()_+~`|}{[]:;?><,./-=';

  const passwordPool = inLc
    ? lowercase
    : inN
    ? numbers
    : inS
    ? symbols
    : inUc
    ? uppercase
    : '';

  const internalPasswordGen = () => {
    let sinPass = '';
    // Add numbers if includeNumbers is true
    if (inN) {
      for (let i = 0; i < nOfN; i++) {
        sinPass += numbers[Math.floor(Math.random() * 10)];
      }
    }
    // Add symbols if includeSymbols is true
    if (inS) {
      for (let i = 0; i < nOfS; i++) {
        sinPass += symbols[Math.floor(Math.random() * 30)];
      }
    }
    // Add lowercase if includeLowercase is true
    if (inLc) {
      for (let i = 0; i < nOfLc; i++) {
        sinPass += lowercase[Math.floor(Math.random() * 26)];
      }
    }
    // Add uppercase if includeUppercase is true
    if (inUc) {
      for (let i = 0; i < nOfUc; i++) {
        sinPass += uppercase[Math.floor(Math.random() * 26)];
      }
    }
    // remove characters if the password is longer than the length
    // add characters if the password is shorter than the length
    if (sinPass.length > length) {
      sinPass = sinPass.slice(0, length);
    } else if (sinPass.length < length) {
      for (let i = 0; i < length - sinPass.length; i++) {
        sinPass +=
          passwordPool[Math.floor(Math.random() * passwordPool.length)];
      }
    }
    // Shuffle the password
    sinPass = sinPass
      .split('')
      .sort(() => Math.random() - 0.5)
      .join('');

    return sinPass;
  };
  for (let i = 0; i < nOfPass; i++) {
    password.push(internalPasswordGen());
  }
  return password;
};

// passwordGen(16, {
//   numberOfNumbers: 4,
//   numberOfSymbols: 2,
//   numberOfPassword: 5,
// });

// Output: [ '{v5n0huD6y.9', '9m3Zw;kb71(a', '1,0o3Xc<ss9x', '3mq|0[Wqiq92', 'fw16[O-hr42q' ];