console.clear();

​

const BASE_62_VALUES = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

​

// convert from decimal to base (default 62)

function to_base(num, base = 62) {

  if (num === 0 ) return BASE_62_VALUES[0]

  result = []

  while (num > 0) {

    r = num % base

    result.unshift(BASE_62_VALUES[r])

    num = Math.floor(num / base)

  }

  return result.join("");

}

​

// Convert to decimal from base (default 62) encoded string

function from_base(value, base = 62) {

  base_10_num = 0

  digit = 0

  value.split('').reverse().forEach(char => { 

    num = BASE_62_VALUES.indexOf(char)

    base_10_num += num * Math.pow(base, digit) 

    digit += 1

  })

  return base_10_num

}

​

function convertToShortUrl(url) {

}

​

console.log(`1:  ${to_base(1)}`);  // => 1

console.log(`decode:  ${from_base(to_base(1))}`);  // => 1

console.log(`98:  ${to_base(98)}`); // => 1A

console.log(`decode:  ${from_base(to_base(98))}`); // => 98

​

console.log(Number.MAX_VALUE);

​

// Reversibility Sampler using 1000 iteration

function randomInteger(min, max) {

  // now rand is from  (min-0.5) to (max+0.5)

  let rand = min - 0.5 + Math.random() * (max - min + 1);

  return Math.round(rand);

}

​

function test_monte_carlo_b10_to_b62_to_b10() {

  [...Array(1000).keys()].forEach(i => {

    seed = randomInteger(1,100000000); 

    b62  = to_base(seed, base=62)

    console.log(seed == from_base(b62))

  })

}

​

test_monte_carlo_b10_to_b62_to_b10();

​

​

​

​

​

​

​

​

​

​

​

​

​