password strength - sl

function _checkPasswordStrength (password = '') {
    password = password.trim();
    const _passwordLength = password.length;

    // Password Strength Additions
    const _passwordLengthTest = _passwordLength >= 8 ? _passwordLength : 0;
    const _numberOfCharactersTest = _passwordLength * 4;

    let _strength = 0;
    let _penalty = 0;

    let _uppercaseLettersTest = 0;
    let _lowercaseLettersTest = 0;
    let _numbersTest = 0;
    let _symbolsTest = 0;
    let _middleNumbersOrSymbolsTest = 0;
    let _requirementsTest = 0;

    let _shortPasswordTest = 0;
    let _lettersOnlyTest = 0;
    let _numbersOnlyTest = 0;
    let _repeatCharactersTest = 0;
    let _consecutiveUppercaseLettersTest = 0;
    let _consecutiveLowercaseLettersTest = 0;
    let _consecutiveNumbersTest = 0;

    _uppercaseLettersTest = password.match(/[A-Z]/g) || 0;
    if(_uppercaseLettersTest !== 0) {
      _uppercaseLettersTest = (
        _passwordLength - _uppercaseLettersTest.length
      ) * 2;
    }

    _lowercaseLettersTest = password.match(/[a-z]/g) || 0;
    if(_lowercaseLettersTest !== 0) {
      _lowercaseLettersTest = (
        _passwordLength - _lowercaseLettersTest.length
      ) * 2;
    }

    _numbersTest = password.match(/[0-9]/g) || 0;
    if(_numbersTest !== 0) {
      _numbersTest = _numbersTest.length * 4;
    }

    _symbolsTest = password.match(/[!-\/.:-@\[-`{-~]/g) || 0;
    if(_symbolsTest !== 0) {
      _symbolsTest = _symbolsTest.length * 6;
    }

    _middleNumbersOrSymbolsTest = password.match(
      /(\w\d[!-\/.:-@\[-`{-~]|[!-\/.:-@\[-`{-~]\w\d|\d[!-\/.:-@\[-`{-~]\w)/g
    ) || 0;
    if(_middleNumbersOrSymbolsTest !== 0) {
      _middleNumbersOrSymbolsTest = _middleNumbersOrSymbolsTest.length * 2;
    }

    // check Passed Password Strength Additions test for _requirementsTest
    const _flags = [_numberOfCharactersTest, _uppercaseLettersTest,
      _lowercaseLettersTest, _numbersTest, _symbolsTest,
      _middleNumbersOrSymbolsTest];
    const _passedMatches = $.grep(_flags, function (el) {
      return el === true;
    }).length;
    _requirementsTest = _passedMatches * 2;

    // Strength Bonus
    _strength = _passwordLengthTest + _numberOfCharactersTest +
      _uppercaseLettersTest + _lowercaseLettersTest + _numbersTest +
      _symbolsTest + _middleNumbersOrSymbolsTest + _requirementsTest;

    // Password Strength Deductions
    _shortPasswordTest = _passwordLength < 8 ?
      Math.min(_strength, 10) : 0;

    _lettersOnlyTest = password.match(/^\w+$/g) ?
      _passwordLength : 0;

    _numbersOnlyTest = password.match(/^\d+$/g) ? _passwordLength : 0;

    _repeatCharactersTest = password.split('').join('').match(/(.)\1+/g) || 0;
    if(_repeatCharactersTest !== 0) {
      _repeatCharactersTest = _repeatCharactersTest.length * 10;
    }

    _consecutiveUppercaseLettersTest = password.match(/[A-Z]{2,}/g) || 0;
    if(_consecutiveUppercaseLettersTest !== 0) {
      _consecutiveUppercaseLettersTest =
        _consecutiveUppercaseLettersTest.length * 2;
    }

    _consecutiveLowercaseLettersTest = password.match(/[a-z]{2,}/g) || 0;
    if(_consecutiveLowercaseLettersTest !== 0) {
      _consecutiveLowercaseLettersTest =
        _consecutiveLowercaseLettersTest.length * 2;
    }

    _consecutiveNumbersTest = password.match(/\d{2,}/g) || 0;
    if(_consecutiveNumbersTest !== 0) {
      _consecutiveNumbersTest =
        _consecutiveNumbersTest.length * 2;
    }

    // Penalty
    _penalty = _shortPasswordTest + _lettersOnlyTest + _numbersOnlyTest +
      _repeatCharactersTest + _consecutiveUppercaseLettersTest +
      _consecutiveLowercaseLettersTest + _consecutiveNumbersTest;

    // Adjusted Strength
    _strength -= _penalty;

    _strength = _strength < 0 ? 0 : _strength > 100 ? 100 : _strength;

    return _strength;
  };