Hex to Binary and Binary to Hex Conversion.

hexToBinUtil.js

var BinToHex = function (uint8array) {
  var len = Math.ceil(uint8array.length / 4);
  var hex = "";
  for (var i=0; i < len; i++) {
    j=i*4;
    var num = uint8array.slice(j,j+4).join('');
    hex += parseInt(num, 2).toString(16).toUpperCase();
  }
  return hex;
}

var HexToBin = function (hex) {
  var len = Math.ceil(hex.length);
  var tmp;
  var sum = "";
  for (var i=0; i < len; i++) {
    tmp = hex.substr(i,1);
    sum += parseInt(tmp, 16).toString(2).padStart(4,'0');
  }
  var uint8arr = new Uint8Array( sum.split('') );
  return uint8arr;
}

HexToBin corrected.