init

bin/utils/observable/index.ts

@@ -0,0 +1,27 @@
+import { Observable } from "../../observable";
+
+const forEach = async <T extends Observable<any[]>>(
+  observable: T,
+  fn: (
+    value: T extends Observable<infer U>
+      ? U extends Array<infer A>
+      ? A
+      : never
+      : never
+  ) => Promise<void>
+) => {
+  const knownValues = new Set();
+  const update = async () => {
+    for (let value of await observable.data) {
+      if (knownValues.has(value)) {
+        continue;
+      }
+      await fn(value);
+      knownValues.add(value);
+    }
+  };
+  await update();
+  observable.subscribe(update);
+};
+
+export { forEach };