A naive tampermonkey script enabling "drag to download" direct links. #user.js

dragToDownload.js

// ==UserScript==
// @name         Drag To Download
// @namespace    
// @version      0.1
// @description  Drag direct links to files to computer.
// @author       Lou Yufan
// @match        http://*/*
// @match        https://*/*
// @grant        none
// ==/UserScript==

// Reference
// Drag out files like Gmail | The CSS Ninja
// http://www.thecssninja.com/javascript/gmail-dragout

// get all links in the page
var links = document.getElementsByTagName("a");

// define the postfixes of files
// add additional postfixes here
var postfixes = [".exe",".zip",".tar.gz"];

// turn postfixed into regex to match the links
// remember the matched filename
// using (?:<pattern>) to group postfixes
// (?:<group>|<group|...) 
var refile = ".*/(.+(?:";
postfixes.forEach(function(postfix){
    refile += "(?:\\"+postfix+")|";
});
refile = new RegExp( refile.slice(0,-1)+"))$", "i" );

// match the regexp
var files = [];
for (var i = 0; i < links.length; ++i){
    if (refile.test(links[i].getAttribute("href"))){
        files.push(links[i]);
    }
}

files.forEach(function(file,ind,arr){
    var downloadurl = file.getAttribute("href");
    // make sure downloadurl is absolute
    var reabs = new RegExp("^https?"); // absolute path test
    var reroot = new RegExp("^/"); // root path test
    if (!reabs.test(downloadurl)){
        if (reroot.test(downloadurl)) {
            downloadurl = location.origin + downloadurl;
        } else {
            downloadurl = location.href + downloadurl;
        }
    }
    // set matched filename as default name
    downloadurl = refile.exec(downloadurl)[1] + ":" + downloadurl;
    // use arbitrary MIME-type
    downloadurl = "application/octet-stream:" + downloadurl;
    // add event
    file.addEventListener("dragstart",function(evt){
        evt.dataTransfer.setData("DownloadURL", downloadurl);
    },false);
});

Reference: Drag out files like Gmaill | CSS Ninja