1:  const hexArray = ["39", "30", "00", "00"];

   2:  const byteArray = hexArray.map(byte => parseInt(byte, 16));

   3:  const buffer = new Uint8Array(byteArray).buffer;

   4:  const view = new DataView(buffer);

   5:  const number = view.getUint32(0, true); // true for Little-endian

   6:  console.log(number); // Output: 12345