add ContestScreenName

AtCoderColorNEWS.js

@@ -5,6 +5,7 @@
 // @author       nullnull
 // @match        https://atcoder.jp
 // @require      https://cdn.rawgit.com/jaredreich/notie.js/a9e4afbeea979c0e6ee50aaf5cb4ee80e65d225d/notie.js
+// @require      https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js
 // ==/UserScript==
 
 (async function () {
@@ -43,19 +44,31 @@
         return `${E(username)}さんのレートが${color[nowRate]}色に変わりました！<br>`;
     }).join("");
 
-    notie.alert(3, string, 20); //20秒後、またはクリックで消える
+    if (string.length > 0) {
+        notie.alert(3, string, 20); //20秒後、またはクリックで消える
+    }
 })();
 
 //Rateを色に変換する
-function getColorIndex(rate){
+function getColorIndex(rate) {
     return Math.min(8, Math.floor(rate / 400));
 }
 
 function getLatestContestScreenName() {
-    //TODO:URLのabc123みたいな奴をとってくる
-    return "agc036";
+    //HTMLの構造が変わったらバグりそう。
+
+    //<a href="/contests/agcXXX">AtCoder Grand Contest XXX</a>
+    let contestScreenName = document.getElementById("collapse-contest").getElementsByClassName("table table-default table-striped table-hover table-condensed small")[2].getElementsByTagName('small')[1].innerHTML;
+
+    //contests/agcXXX
+    contestScreenName = contestScreenName.split('"')[1];
+
+    //agcXXX
+    contestScreenName = contestScreenName.split('/').pop();
+
+    return contestScreenName;
 }
 
 async function getContestResultData(contestScreenName) {
     return await $.ajax(`https://atcoder.jp/contests/${contestScreenName}/results/json`);
-}
+}