First workable server.

vendor/deno.land/std@0.191.0/async/deferred.ts

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+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+// This module is browser compatible.
+
+// TODO(ry) It'd be better to make Deferred a class that inherits from
+// Promise, rather than an interface. This is possible in ES2016, however
+// typescript produces broken code when targeting ES5 code.
+// See https://github.com/Microsoft/TypeScript/issues/15202
+// At the time of writing, the github issue is closed but the problem remains.
+export interface Deferred<T> extends Promise<T> {
+  readonly state: "pending" | "fulfilled" | "rejected";
+  resolve(value?: T | PromiseLike<T>): void;
+  // deno-lint-ignore no-explicit-any
+  reject(reason?: any): void;
+}
+
+/**
+ * Creates a Promise with the `reject` and `resolve` functions placed as methods
+ * on the promise object itself.
+ *
+ * @example
+ * ```typescript
+ * import { deferred } from "https://deno.land/std@$STD_VERSION/async/deferred.ts";
+ *
+ * const p = deferred<number>();
+ * // ...
+ * p.resolve(42);
+ * ```
+ */
+export function deferred<T>(): Deferred<T> {
+  let methods;
+  let state = "pending";
+  const promise = new Promise<T>((resolve, reject) => {
+    methods = {
+      async resolve(value: T | PromiseLike<T>) {
+        await value;
+        state = "fulfilled";
+        resolve(value);
+      },
+      // deno-lint-ignore no-explicit-any
+      reject(reason?: any) {
+        state = "rejected";
+        reject(reason);
+      },
+    };
+  });
+  Object.defineProperty(promise, "state", { get: () => state });
+  return Object.assign(promise, methods) as Deferred<T>;
+}