the dic look up approach

dic-lookup.js

function maxLength(digit) {
  return Math.pow(8, digit) * 9;
}

const getDic = digit =>
  Array.from(new Array(Math.pow(10, digit) - 1))
    .map((_, idx) => idx + 1)
    .filter(v => v >= Math.pow(10, digit - 1));
function random(max) {
  return Math.floor(Math.random() * (max + 1));
}

function checkConsecutive(nPlus1, n) {
  return nPlus1 - n !== 1;
}

function haveNoConsecutive(
  arr,
  isValid = true,
  idx = 0
) {
  if (!isValid) {
    return false;
  }
  return idx === arr.length - 1
    ? isValid
    : haveNoConsecutive(
        arr,
        checkConsecutive(arr[idx + 1], arr[idx]),
        idx + 1
      );
}

const patternArr = [
  /11/,
  /22/,
  /33/,
  /44/,
  /55/,
  /66/,
  /77/,
  /88/,
  /99/,
  /00/
];

function haveNoDuplicate(numberString, idx = 0) {
  const pattern = patternArr[idx];
  if (pattern.test(numberString)) {
    return false;
  }
  if (idx === patternArr.length - 1) {
    return true;
  }
  return haveNoDuplicate(numberString, idx + 1);
}

function getPin(digit) {
  const internalDic = getDic(digit);
  // console.log(internalDic);
  return function ensureInShape(
    dic = internalDic,
    idx = 1
  ) {
    const pin = dic[idx];
    const stringPin = pin.toString();
    let havDuplicate = !haveNoDuplicate(
      stringPin
    );

    if (havDuplicate) {
      return ensureInShape(
        [
          ...dic.slice(0, idx),
          ...dic.slice(idx + 1)
        ],
        random(dic.length - 2)
      );
    }

    const haveConsecutive = !haveNoConsecutive(
      stringPin
        .split('')
        .map(item => parseInt(item))
    );

    if (haveConsecutive) {
      return ensureInShape(
        [
          ...dic.slice(0, idx),
          ...dic.slice(idx + 1)
        ],
        random(dic.length - 2)
      );
    }
    return pin;
  };
}

function pick(digit, count) {
  const set = new Set();
  const maxlen = maxLength(digit - 1);
  if (count > maxlen) {
    throw new Error(
      `cannot have more than ${maxlen} combinations for ${digit} digit(s)`
    );
  }

  const generator = getPin(digit);
  return function recrusive() {
    if (set.size === count) {
      return set;
    }
    set.add(generator());
    return recrusive();
  };
}

module.exports = pick;