viewerCounter and websocket JS modules

web/static/js/modules/viewerCounter.js

@@ -0,0 +1,29 @@
+/**
+ * ViewerCounter show the number of active viewers
+ */
+export class ViewerCounter {
+    /**
+     * @param {HTMLElement} element 
+     * @param {String} streamName 
+     */
+    constructor(element, streamName) {
+        this.element = element;
+        this.url = "/_stats/" + streamName;
+    }
+
+    /**
+     * Regulary update counter
+     * 
+     * @param {Number} updatePeriod 
+     */
+    regularUpdate(updatePeriod) {
+        setInterval(this._refreshViewersCounter, updatePeriod);
+    }
+
+    _refreshViewersCounter() {
+        fetch(this.url)
+            .then(response => response.json())
+            .then((data) => this.element.innerText = data.ConnectedViewers)
+            .catch(console.log);
+    }
+}