feat: initial commit at project root

internal/timer/timer.js

@@ -0,0 +1,32 @@
+/**
+ * CallTimer wraps Node's setTimeout/clearTimeout to allow session cancellations.
+ */
+export class CallTimer {
+  /**
+   * @param {number} durationMs 
+   * @param {function} onExpiry 
+   */
+  constructor(durationMs, onExpiry) {
+    this.timer = setTimeout(onExpiry, durationMs);
+  }
+
+  /**
+   * Cancels the active timer.
+   */
+  stop() {
+    if (this.timer) {
+      clearTimeout(this.timer);
+      this.timer = null;
+    }
+  }
+}
+
+/**
+ * Starts a session timeout timer.
+ * @param {number} durationMs 
+ * @param {function} onExpiry 
+ * @returns {CallTimer}
+ */
+export function startTimer(durationMs, onExpiry) {
+  return new CallTimer(durationMs, onExpiry);
+}