prevent memory leak from setTimeout

Author: myandrienko

packages/client/src/timers/index.ts

@@ -73,7 +73,17 @@ class TimerWorker {
     }
 
     const id = this.getTimerId();
-    this.callbacks.set(id, callback);
+
+    this.callbacks.set(id, () => {
+      callback();
+
+      // Timeouts are one-off operations, so no need to keep callback reference
+      // after timer has fired
+      if (type === 'setTimeout') {
+        this.callbacks.delete(id);
+      }
+    });
+
     this.sendMessage({ type, id, timeout });
     return id;
   }

packages/client/src/timers/worker.ts

@@ -12,10 +12,13 @@ self.addEventListener('message', (event: MessageEvent) => {
     case 'setInterval':
       timerIdMapping.set(
         request.id,
-        (request.type === 'setTimeout' ? setTimeout : setInterval)(
-          () => tick(request.id),
-          request.timeout,
-        ),
+        (request.type === 'setTimeout' ? setTimeout : setInterval)(() => {
+          tick(request.id);
+
+          if (request.type === 'setTimeout') {
+            timerIdMapping.delete(request.id);
+          }
+        }, request.timeout),
       );
       break;