hex to string and string to hex

hex.ts

/**
   * String to Hex
   */
function stringToHex(str: Readonly<string>) {
  let hex, i
  let result = ''
  for (i = 0; i < str.length; i++) {
    hex = str.charCodeAt(i).toString(16)
    result += hex
  }
  return result
}

/**
 * Hex to string
 */
function hexToString(_hex: Readonly<string>) {
  const hex = _hex.toString() //force conversion
  let str = ''
  for (let i = 0; i < hex.length; i += 2)
    str += String.fromCharCode(parseInt(hex.substr(i, 2), 16))
  return str
}