Saren / HKGolden captcha solver

// ==UserScript==
// @name        HKGolden captcha solver
// @namespace   Saren
// @description Solves HKGolden's login captcha
// @include     *.hkgolden.com/login.aspx*
// @version     0.0.1
// @grant       none
// ==/UserScript==


function getBase64Image(img) {
    // Create an empty canvas element
    var canvas = document.createElement("canvas");
    canvas.width = img.width;
    canvas.height = img.height;

    // Copy the image contents to the canvas
    var ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0);

    // Get the data-URL formatted image
    // Firefox supports PNG and JPEG. You could check img.src to
    // guess the original format, but be aware the using "image/jpg"
    // will re-encode the image.
    var dataURL = canvas.toDataURL("image/png");

    return dataURL.replace(/^data:image\/(png|jpg);base64,/, "");
}

$(function () {
    var imgData = getBase64Image(document.getElementById("ctl00_ContentPlaceHolder1_imgChkCode"));
    $.post("https://apps.saren.me/hkgcs/", {captcha: imgData}, function (data) {
        $("#ctl00_ContentPlaceHolder1_txtChkCode").val(data.result);
    });
});