danbooru系のサイトで画像をクリック時にDLする

danbooruDL.user.js

// ==UserScript==
// @name         danbooru dl support
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  try to take over the world!
// @author       karubabu
// @match        https://*/post/show/*
// @grant        GM_download
// @grant        GM_notification
// ==/UserScript==

function exist_png(){
    return document.getElementsByClassName("original-file-unchanged").length === 1;
}

function get_url(is_png=false){
    if(is_png === true){
        return document.getElementsByClassName("original-file-unchanged")[0].href;
    }
    return document.getElementsByClassName("original-file-changed")[0].href;
}

function download(furl, fname){
    GM_download({url: furl, name: fname, onload: GM_notification(fname + " complete!")});
}

(function() {
    'use strict';

    console.log("url: " + get_url(exist_png()));
    var pic_url = get_url(exist_png());
    var file_name = decodeURI(pic_url.match(".*/([^\?#;/:]+).*$")[1]);
    console.log("filename: " + file_name);

    var sub = document.getElementById("right-col");
    sub.addEventListener("click", function(e){
        download(pic_url, file_name);
    });
})();