Converting Hexadecimal To Float In JavaScript

Answer :

Another possibility is to parse the digits separately, splitting the string up in two and treating both parts as ints during the conversion and then add them back together.

function parseFloat(str, radix)
{
    var parts = str.split(".");
    if ( parts.length > 1 )
    {
        return parseInt(parts[0], radix) + parseInt(parts[1], radix) / Math.pow(radix, parts[1].length);
    }
    return parseInt(parts[0], radix);
}

var myno = 28.4382;
var convno = myno.toString(16);
var f = parseFloat(convno, 16);
console.log(myno + " -> " + convno + " -> " + f);

Try this.

The string may be raw data (simple text) with four characters (0 - 255) or
a hex string "0xFFFFFFFF" four bytes in length.

jsfiddle.net

var str = '0x3F160008';

function parseFloat(str) {
    var float = 0, sign, order, mantissa, exp,
    int = 0, multi = 1;
    if (/^0x/.exec(str)) {
        int = parseInt(str, 16);
    }
    else {
        for (var i = str.length -1; i >=0; i -= 1) {
            if (str.charCodeAt(i) > 255) {
                console.log('Wrong string parameter');
                return false;
            }
            int += str.charCodeAt(i) * multi;
            multi *= 256;
        }
    }
    sign = (int >>> 31) ? -1 : 1;
    exp = (int >>> 23 & 0xff) - 127;
    mantissa = ((int & 0x7fffff) + 0x800000).toString(2);
    for (i=0; i<mantissa.length; i+=1) {
        float += parseInt(mantissa[i]) ? Math.pow(2, exp) : 0;
        exp--;
    }
    return float*sign;
}

Please try this:

function hex2dec(hex) {
    hex = hex.split(/\./);
    var len = hex[1].length;
    hex[1] = parseInt(hex[1], 16);
    hex[1] *= Math.pow(16, -len);
    return parseInt(hex[0], 16) + hex[1];
}

function hex2dec(hex) {
  hex = hex.split(/\./);
  var len = hex[1].length;
  hex[1] = parseInt(hex[1], 16);
  hex[1] *= Math.pow(16, -len);
  return parseInt(hex[0], 16) + hex[1];
}



// ----------
// TEST
// ----------

function calc(hex) {
  let dec = hex2dec(hex);
  msg.innerHTML = `dec: <b>${dec}</b><br>hex test: <b>${dec.toString(16)}</b>`
} 

let init="bad.a55";
inp.value=init;
calc(init);

<input oninput="calc(this.value)" id="inp" /><div id="msg"></div>