code: function int2Str36(num) {
      let baseIdx = d36.length;
      let result = [];
      let empty = null;
      if (num === 0) return '0';
      for (let i = 0; i < baseIdx; i++) {
          let d = d36[i];
          let c = 0;
          if (d <= num) {
              c = Math.trunc(num/d);
              num -= d * c;
              c = encodeCharCode2Int36(c);
              empty = encodeCharCode2Int36(0);
          } else {
              c = empty;
          }
          if (c) result.push(c);
      }
      return String.fromCharCode.apply(null, result);
  }
docs: generates 36 capacity digits string from integer result is string of [0-1A-Z]
  @param {number} num
  @returns {string}