Encode and decode numbers into codes

encode.js

const [ns, s] = process.hrtime();

const nsTime = (s * 1e6 + ns);

function encode(num, digits = 15, off = 0) {

  const rand = off ? Math.random().toString(26).substring(1, 1 + off) : '';
  const str = (num.toString(26) + rand).split('');
  let input = str.map(ch => ch === '.' ? '-' : (parseInt(ch, 26) + 10).toString(36)).join('').toUpperCase();

  input = input.split('')
  input.unshift('{');
  input.push('}');

  const table = [];

  for (let x = 0; x < input.length; x++) {
    table.push(input.slice())
    input.push(input.shift());
  }

  table.sort();

  const encoded = table.map(row => row[row.length - 1]);

  const reconstructed = [];

  for (let x = 0, y; x < encoded.length;) {
    const ch = encoded[x];
    for (y = x; encoded[y] === ch; y++) {
    }
    const count = y - x;

    if (count === 1) {
      if (ch === '{') {
        reconstructed.push('0');
      } else if (ch === '}') {
        reconstructed.push('1');
      } else {
        reconstructed.push(ch);
      }
    } else {
      let left = count;
      while (left > 0) {
        if (left > 9) {
          reconstructed.push(ch + 9);
          left -= 9;
        } else if (left === 1) {
          reconstructed.push(ch);
          left -= 1;
        } else {
          reconstructed.push(ch + left);
          left = 0;
        }
      }
    }
    x += count;
  }

  const output = reconstructed.join('');

  if (output.length < digits) {
    return encode(num, digits, off + 1);
  }

  return output;
}

function decode(encoded) {

  const input = [];

  encoded = encoded.split('')
    .forEach((ch, i, inp) => {
      if (ch.match(/^[A-Z-]+/)) {
        input.push(ch);
      } else if (ch === '0') {
        input.push('{');
      } else if (ch === '1') {
        input.push('}');
      } else {
        let count = parseInt(ch);
        while (count-- > 1) {
          input.push(inp[i - 1]);
        }
      }
    });

  const table = [];

  for (let x = 0; x < input.length; x++) {
    table.push('');
  }

  while (table[0].length < input.length) {

    for (let x = 0; x < input.length; x++) {
      table[x] = input[x] + table[x];
    }
    table.sort();

  }

  let match = table.find(x => x.match(/^[{][^}]+[}]$/));

  match = match.substring(1, match.length - 1);

  match = parseInt(match.split('').map(ch => ch === '-' ? '.' : (parseInt(ch, 36) - 10).toString(26)).join(''), 26);

  return match;
}

for (let x = 1; x < 1e20; x *= 2) {
  console.log(x, encode(x), decode(encode(x)));
}

console.log(nsTime, encode(nsTime), decode(encode(nsTime)));