How do I implement hex2bin()?

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() and json_encode() on PHP side.

How do I convert the hexadecimal string in binary string, with JavaScript?

Solution 1:

To answer your question:

function Hex2Bin(n){if(!checkHex(n))return 0;return parseInt(n,16).toString(2)}

Here are some further functions you may find useful for working with binary data:

//Useful Functions
function checkBin(n){return/^[01]{1,64}$/.test(n)}
function checkDec(n){return/^[0-9]{1,64}$/.test(n)}
function checkHex(n){return/^[0-9A-Fa-f]{1,64}$/.test(n)}
function pad(s,z){s=""+s;return s.length<z?pad("0"+s,z):s}
function unpad(s){s=""+s;return s.replace(/^0+/,'')}

//Decimal operations
function Dec2Bin(n){if(!checkDec(n)||n<0)return 0;return n.toString(2)}
function Dec2Hex(n){if(!checkDec(n)||n<0)return 0;return n.toString(16)}

//Binary Operations
function Bin2Dec(n){if(!checkBin(n))return 0;return parseInt(n,2).toString(10)}
function Bin2Hex(n){if(!checkBin(n))return 0;return parseInt(n,2).toString(16)}

//Hexadecimal Operations
function Hex2Bin(n){if(!checkHex(n))return 0;return parseInt(n,16).toString(2)}
function Hex2Dec(n){if(!checkHex(n))return 0;return parseInt(n,16).toString(10)}

Solution 2:

JavaScript doesn't have support for binary data. Nevertheless you can emulate this with regular strings.

var hex = "375771", // ASCII HEX: 37="7", 57="W", 71="q"
    bytes = [],
    str;

for(var i=0; i< hex.length-1; i+=2){
    bytes.push(parseInt(hex.substr(i, 2), 16));
}

str = String.fromCharCode.apply(String, bytes);

alert(str); // 7Wq

Solution 3:

function hex2bin(hex)
{
    var bytes = [], str;

    for(var i=0; i< hex.length-1; i+=2)
        bytes.push(parseInt(hex.substr(i, 2), 16));

    return String.fromCharCode.apply(String, bytes);    
}

thanks to Andris!

Other useful information about this topic (dex2bin,bin2dec) can be found here. According to that, here is a bin2hex solution:

parseInt(1100,2).toString(16); //--> c