Add a download selected button for UCAS SEP files.

downloader_for_sep.js

// ==UserScript==
// @name         UCAS SEP Download Selected Files
// @namespace    http://li-yiyang.github.io/
// @version      0.1
// @description  Add a download selected button for UCAS SEP files. 
// @author       凉凉
// @match        http*://course.ucas.ac.cn/portal/site/*/tool/*
// @grant        none
// ==/UserScript==
// run after window is loaded
window.onload = (function () {
    // base url of the content
    let base_url = "https://course.ucas.ac.cn/access/content";
    
    // Add a button to page.
    // Get the bar.
    let bar = document.getElementsByClassName("col-lg-6 col-md-8 col-sm-8 col-xs-12 btn-group btn-group-sm")[0];
    // or at the bottom
    // let bar = document.getElementById("bottompadding");

    // make a button
    let btm = document.createElement("button");
    btm.innerHTML = "Download Selected";
    
    btm.onclick = function () {
	    let table = document.getElementsByTagName("tr");
	    let length = table.length;

    	// the first two element of the web table is a total check
	    // and the second one is a directory path, which are useless
	    for (var i = 2; i < length; i++) {
	        let item = table[i].querySelector("[name=selectedMembers]");
	    
	        if (item.checked) {
		        let url = base_url + item.value;
		        let fname = item.value.split("/").slice(-1)[0];
		
		        (function (url) {
		            // you can change the download method
		            window.open(url, "_blank");
		        })(url);
		
		        console.log(url)
	        }
	    }
    }

    // use the same style as copy button
    btm.style = "margin:0";
    btm.setAttribute("class", "btn btn-default");
    btm.setAttribute("id", "download-button");

    // add the item to the bar
    bar.appendChild(btm);
})();