JavaScript to convert IPv4 addresses from dotted-decimal notation to integers and back.

ipconv.js

function ip2int (ip) {
    var ipVal = 0;
    ip.split(".").forEach(function (octet, i, arr) {
        var exp = 8 * (arr.length - i - 1);
        ipVal += octet * Math.pow(2, exp);
    });

    return ipVal;
}

function int2ip (n) {
    var octets = [];
    var len = 2;
    var hexString = n.toString(16);
    if (hexString.length % 2) {
        hexString = "0" + hexString;
    }

    for (var i=0; i<= hexString.length-len; i+=len) {
        octets.push(parseInt(hexString.substr(i, len), 16));
    }

    return octets.join(".");
}