A bookmarklet for downloading currently viewed Flickr image in the biggest available size

download-current-flickr-image.js

/*jslint browser, maxlen: 80 */
/*global DOMParser, fetch */

(function () {
    "use strict";

    var originalSizeLink = document.querySelector(".Original > a");
    var canonicalUrl = document.querySelector("#canonicalurl").href;
    var biggestSizeUrl = canonicalUrl + "/sizes/k/";
    var secondBiggestSizeUrl = canonicalUrl + "/sizes/h/";

    function downloadImage(href) {
        var a = document.createElement("a");

        a.href = href;
        a.download = document.title.split(" |")[0] + ".jpg";
        document.body.appendChild(a);
        a.click();
    }

    function getHrefAndDownloadImage(responseText) {
        var href = new DOMParser()
            .parseFromString(responseText, "text/html")
            .querySelector("#allsizes-photo > img")
            .src;

        downloadImage(href);
    }

    if (originalSizeLink) {
        return originalSizeLink.click();
    }

    fetch(biggestSizeUrl)
        .then(function (response) {
            return (response.ok && response.url === biggestSizeUrl)
                ? response
                : fetch(secondBiggestSizeUrl);
        })
        .then(function (response) {
            return response.text();
        })
        .then(getHrefAndDownloadImage);
}());

How to add it to Chrome?
I created a new bookmark and edited the URL as javascript:your code
But nothing happen when clicked!!