Byte to Hex and Hex to Byte in JavaScript.

byteToHex.js

const byteToHex = (byte) => {
  const key = '0123456789abcdef'
  let bytes = new Uint8Array(byte)
  let newHex = ''
  let currentChar = 0
  for (let i=0; i<bytes.length; i++) { // Go over each 8-bit byte
    currentChar = (bytes[i] >> 4)      // First 4-bits for first hex char
    newHex += key[currentChar]         // Add first hex char to string
    currentChar = (bytes[i] & 15)      // Erase first 4-bits, get last 4-bits for second hex char
    newHex += key[currentChar]         // Add second hex char to string
  }
  return newHex
}
// byteToHex([104,101,108,108,111])
// => '68656c6c6f'

hexToByte.js

const hexToByte = (hex) => {
  const key = '0123456789abcdef'
  let newBytes = []
  let currentChar = 0
  let currentByte = 0
  for (let i=0; i<hex.length; i++) {   // Go over two 4-bit hex chars to convert into one 8-bit byte
    currentChar = key.indexOf(hex[i])
    if (i%2===0) { // First hex char
      currentByte = (currentChar << 4) // Get 4-bits from first hex char
    }
    if (i%2===1) { // Second hex char
      currentByte += (currentChar)     // Concat 4-bits from second hex char
      newBytes.push(currentByte)       // Add byte
    }
  }
  return new Uint8Array(newBytes)
}
// hexToByte('68656c6c6f')
// => [104, 101, 108, 108, 111]

Thank you, your code has helped me with one of my projects! 😉

Thank you, your code has helped me with one of my projects! 😉