Freez gif js code

gistfile1.txt

var freezeGif = function (img) {
    return new Promise(function (resolve) {
        var i = new Image();
        i.src = img;

        i.onload = function () {
            var c = document.createElement('canvas');
            var w  = c.width = i.width;
            var h = c.height = i.height;

            c.getContext('2d').drawImage(i, 0, 0, w, h);
            resolve(c.toDataURL('image/gif'));
        };
    });
};

input url to a gif, output a b64encoded image