6 files changed, 65 insertions, 1 deletions
diff --git a/cli/js/globals.ts b/cli/js/globals.ts
index ada491bde..d71a96d39 100644
--- a/cli/js/globals.ts
+++ b/cli/js/globals.ts
@@ -179,6 +179,14 @@ export function readOnly(value: unknown): PropertyDescriptor {
   };
 }
 
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function getterOnly(getter: () => any): PropertyDescriptor {
+  return {
+    get: getter,
+    enumerable: true
+  };
+}
+
 // https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope
 export const windowOrWorkerGlobalScopeMethods = {
   atob: writable(textEncoding.atob),
diff --git a/cli/js/lib.deno.window.d.ts b/cli/js/lib.deno.window.d.ts
index 737971d94..e4ab6b70d 100644
--- a/cli/js/lib.deno.window.d.ts
+++ b/cli/js/lib.deno.window.d.ts
@@ -13,6 +13,8 @@ declare interface Window extends WindowOrWorkerGlobalScope {
   onload: Function | undefined;
   onunload: Function | undefined;
   crypto: Crypto;
+  close: () => void;
+  closed: boolean;
   Deno: typeof Deno;
 }
 
diff --git a/cli/js/runtime_main.ts b/cli/js/runtime_main.ts
index a59e7513b..4c506e0ce 100644
--- a/cli/js/runtime_main.ts
+++ b/cli/js/runtime_main.ts
@@ -10,8 +10,10 @@
 import * as Deno from "./deno.ts";
 import * as domTypes from "./web/dom_types.ts";
 import * as csprng from "./ops/get_random_values.ts";
+import { exit } from "./ops/os.ts";
 import {
   readOnly,
+  getterOnly,
   writable,
   windowOrWorkerGlobalScopeMethods,
   windowOrWorkerGlobalScopeProperties,
@@ -21,6 +23,7 @@ import { internalObject } from "./internals.ts";
 import { setSignals } from "./signals.ts";
 import { replLoop } from "./repl.ts";
 import { LocationImpl } from "./web/location.ts";
+import { setTimeout } from "./web/timers.ts";
 import * as runtime from "./runtime.ts";
 import { symbols } from "./symbols.ts";
 import { log, immutableDefine } from "./util.ts";
@@ -31,6 +34,26 @@ import { log, immutableDefine } from "./util.ts";
 // @ts-ignore
 Deno[symbols.internal] = internalObject;
 
+let windowIsClosing = false;
+
+function windowClose(): void {
+  if (!windowIsClosing) {
+    windowIsClosing = true;
+    // Push a macrotask to exit after a promise resolve.
+    // This is not perfect, but should be fine for first pass.
+    Promise.resolve().then(() =>
+      setTimeout.call(
+        null,
+        () => {
+          // This should be fine, since only Window/MainWorker has .close()
+          exit(0);
+        },
+        0
+      )
+    );
+  }
+}
+
 export const mainRuntimeGlobalProperties = {
   window: readOnly(globalThis),
   self: readOnly(globalThis),
@@ -38,7 +61,9 @@ export const mainRuntimeGlobalProperties = {
   // TODO(bartlomieju): from MDN docs (https://developer.mozilla.org/en-US/docs/Web/API/WorkerGlobalScope)
   // it seems those two properties should be availble to workers as well
   onload: writable(undefined),
-  onunload: writable(undefined)
+  onunload: writable(undefined),
+  close: writable(windowClose),
+  closed: getterOnly(() => windowIsClosing)
 };
 
 let hasBootstrapped = false;
diff --git a/cli/tests/058_tasks_microtasks_close.ts b/cli/tests/058_tasks_microtasks_close.ts
new file mode 100644
index 000000000..11de55a38
--- /dev/null
+++ b/cli/tests/058_tasks_microtasks_close.ts
@@ -0,0 +1,18 @@
+console.log("sync 1");
+setTimeout(() => {
+  console.log("setTimeout 1");
+  Promise.resolve().then(() => {
+    console.log("Promise resolve in setTimeout 1");
+  });
+});
+Promise.resolve().then(() => {
+  console.log("promise 1");
+});
+window.close();
+console.log("sync 2");
+setTimeout(() => {
+  console.log("setTimeout 2");
+});
+setTimeout(() => {
+  console.log("setTimeout 3");
+}, 100);
diff --git a/cli/tests/058_tasks_microtasks_close.ts.out b/cli/tests/058_tasks_microtasks_close.ts.out
new file mode 100644
index 000000000..218273cab
--- /dev/null
+++ b/cli/tests/058_tasks_microtasks_close.ts.out
@@ -0,0 +1,6 @@
+sync 1
+sync 2
+promise 1
+setTimeout 1
+Promise resolve in setTimeout 1
+setTimeout 2
diff --git a/cli/tests/integration_tests.rs b/cli/tests/integration_tests.rs
index 02c46840e..f8651869b 100644
--- a/cli/tests/integration_tests.rs
+++ b/cli/tests/integration_tests.rs
@@ -1078,6 +1078,11 @@ itest!(_057_revoke_permissions {
   output: "057_revoke_permissions.out",
 });
 
+itest!(_058_tasks_microtasks_close {
+  args: "run 058_tasks_microtasks_close.ts",
+  output: "058_tasks_microtasks_close.ts.out",
+});
+
 itest!(js_import_detect {
   args: "run --reload js_import_detect.ts",
   output: "js_import_detect.ts.out",