Zxing生成二维码，16进制数据转字符串失败

function hextoString(hex: string): string { 
  let hexString = hex 
  if (hex.indexOf('0x') === 0) { 
    hexString = hex.substring(2,hex.length) 
  } 
  let arr = hexString.split('') 
  let out = '' 
  for (let index = 0; index < hexString.length / 2; index++) { 
    let tmp = arr[index * 2] + arr[index * 2 + 1] 
    let charValue = String.fromCharCode(parseInt(tmp,16)) 
    out += charValue 
  } 
  return out 
}