`var s = $('img.captchaImage').first().attr('src');
var img = "https://***/" + s + ".png";
var canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0);
var dataURL = canvas.toDataURL("image/jpeg", 0.5);
dataURL = dataURL.replace(/^data:image/(png|jpg);base64,/, "");
encodeURIComponent(dataURL);`