Add function

Chrome/content.js

@@ -1,5 +1,4 @@
 // Config
-
 const CACHE_TTL = 5 * 60 * 1000; // Cache Time-To-Live in milliseconds
 const CONCURRENT_LIMIT = 4; // Max Parallel Fetch Requests
 
@@ -198,6 +197,7 @@ async function refreshScores(force = true) {
     updateSidebar();
     updateTotalScore();
 
+
     await storeStorageCache();
 }
 
@@ -244,6 +244,33 @@ async function refreshSingleTask(url, task) {
 }
 
 function createControls() {
+    const prev = document.createElement("button");
+    const next = document.createElement("button");
+    prev.setAttribute("hidden",true);
+    next.setAttribute("hidden",true);
+    prev.className = "move-button";
+    next.className = "move-button";
+    if(!!window.location.href.match(`${baseURL}/tasks`)){
+        prev.textContent = "Prev";
+        next.textContent = "Next";
+        const prevUrl = moveProblem(-1);
+        const nextUrl = moveProblem(+1);
+        if(!!prevUrl){
+            prev.removeAttribute("hidden");
+        }
+        if(!!nextUrl){
+            next.removeAttribute("hidden");
+        }
+        prev.addEventListener("click", () => {
+            sessionStorage.setItem("cms-extension-scroll", window.scrollY);
+            window.location.href = prevUrl;
+        })
+        next.addEventListener("click", () => {
+            sessionStorage.setItem("cms-extension-scroll", window.scrollY);
+            window.location.href = nextUrl;
+        })
+    }
+
     const controlsContainer = document.createElement("div");
     controlsContainer.className = "cms-extension-controls";
     const totalScoreContainer = document.createElement("div");
@@ -263,6 +290,8 @@ function createControls() {
             }
         })
     );
+    controlsContainer.appendChild(prev);
+    controlsContainer.appendChild(next);
     controlsContainer.appendChild(totalScoreContainer);
     controlsContainer.appendChild(refreshButton);
     // last refreshed timestamp
@@ -351,3 +380,55 @@ function updateSidebar() {
         }
     });
 }
+
+function moveProblem(delta) {
+    const urlSplit = splitProblemURL();
+    const problem = urlSplit[1];
+
+    let query;
+    if(delta === +1){
+        query = handleMove(problem,1)
+    }else if(delta === -1){
+        query = handleMove(problem,-1)
+    }
+
+    if(!query)
+        return query;
+
+    return urlSplit[0]+query+urlSplit[2];
+}
+
+function handleMove(item,delta){
+    const headers = document.getElementsByClassName("nav-header");
+
+
+    let index = Array.from(headers).findIndex(el => {
+        const span = el.querySelector("span");
+        return span && span.textContent.trim() === item;
+    });
+
+    index += delta;
+
+    if(index < 0 || index >= headers.length){
+        return null;
+    }
+
+    const target = headers[index].querySelector("span").textContent;
+    return target;
+}
+
+function splitProblemURL() {
+    const u = window.location.href
+        .split(/\?submission_id/)[0];
+
+    const parts = u.split("/").filter(Boolean); 
+
+    const i = parts.indexOf("tasks");
+    if (i === -1 || i + 2 >= parts.length) return null;
+
+    const prefix = "https://" + parts.slice(1, i + 1).join("/") + "/";
+    const problem = parts[i + 1];
+    const page = "/"+parts.slice(i + 2).join("/");
+
+    return [prefix, problem, page];
+}

Chrome/style.css

@@ -37,3 +37,15 @@
   box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
   font-weight: bold;
 }
+.move-button {
+  background-color: #f0f0f0;
+  padding: 10px;
+  border: none;
+  cursor: pointer;
+  border-radius: 5px;
+  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
+  font-weight: bold;
+}
+.move-button:hover {
+  background-color: #e5e5e5;
+}