How do I implement hex2bin()?

Question

I need to communicate between Javascript and PHP (I use jQuery for AJAX), but the output of the PHP script may contain binary data. That\'s why I use bin2hex()

Answer 1

Although not an answer to the actual question, it is perhaps useful in this case to also know how to reverse the process:

function bin2hex (bin)
{

  var i = 0, l = bin.length, chr, hex = ''

  for (i; i < l; ++i)
  {

    chr = bin.charCodeAt(i).toString(16)

    hex += chr.length < 2 ? '0' + chr : chr

  }

  return hex

}

As an example, using hex2bin on b637eb9146e84cb79f6d981ac9463de1 returns ¶7ëFèL·mÉF=á, and then passing this to bin2hex returns b637eb9146e84cb79f6d981ac9463de1.

It might also be useful to prototype these functions to the String object:

String.prototype.hex2bin = function ()
{

  var i = 0, l = this.length - 1, bytes = []

  for (i; i < l; i += 2)
  {
    bytes.push(parseInt(this.substr(i, 2), 16))
  }

  return String.fromCharCode.apply(String, bytes)   

}

String.prototype.bin2hex = function ()
{

  var i = 0, l = this.length, chr, hex = ''

  for (i; i < l; ++i)
  {

    chr = this.charCodeAt(i).toString(16)

    hex += chr.length < 2 ? '0' + chr : chr

  }

  return hex

}

alert('b637eb9146e84cb79f6d981ac9463de1'.hex2bin().bin2hex())