Implement select counter + select-all + select-none.

static/index.js

@@ -94,3 +94,38 @@ function loadClans() {
             console.error('There has been a problem with your fetch operation:', error);
         });
 }
+
+function updateSelectedPlayers(sender) {
+    const playerList = sender.parentElement.parentElement.parentElement;
+    const checkCounter = playerList.parentElement.parentElement.querySelector('span.badge');
+    let counter = 0;
+
+    Array.from(playerList.children).forEach(p => {
+       if (p.querySelector('input[type="checkbox"]:checked'))
+           counter++;
+    });
+
+    checkCounter.innerText = counter;
+}
+
+function selectAllPlayers(playerListId) {
+    const playerList = document.getElementById(playerListId);
+    const checkCounter = playerList.parentElement.parentElement.querySelector('span.badge');
+
+    Array.from(playerList.children).forEach(p => {
+        p.querySelector('input[type="checkbox"]').checked = true;
+    });
+
+    checkCounter.innerText = playerList.children.length;
+}
+
+function deselectAllPlayers(playerListId) {
+    const playerList = document.getElementById(playerListId);
+    const checkCounter = playerList.parentElement.parentElement.querySelector('span.badge');
+
+    Array.from(playerList.children).forEach(p => {
+        p.querySelector('input[type="checkbox"]').checked = false;
+    });
+
+    checkCounter.innerText = 0;
+}