LibWeb: Implement window.queueMicrotask(callback)

This API allows authors to schedule a serialized JS callback that will
get invoked at the next spec-allowed opportunity.

2 files changed, 25 insertions, 0 deletions

diff --git a/Userland/Libraries/LibWeb/Bindings/WindowObject.cpp b/Userland/Libraries/LibWeb/Bindings/WindowObject.cpp
index 0be35f2cf6..cf9ae65202 100644
--- a/Userland/Libraries/LibWeb/Bindings/WindowObject.cpp
+++ b/Userland/Libraries/LibWeb/Bindings/WindowObject.cpp
@@ -80,6 +80,8 @@ void WindowObject::initialize_global_object()
     define_native_function("atob", atob, 1, attr);
     define_native_function("btoa", btoa, 1, attr);
 
+    define_native_function("queueMicrotask", queue_microtask, 1, attr);
+
     define_native_function("getComputedStyle", get_computed_style, 1, attr);
     define_native_function("matchMedia", match_media, 1, attr);
 
@@ -338,6 +340,27 @@ JS_DEFINE_NATIVE_FUNCTION(WindowObject::cancel_animation_frame)
     return JS::js_undefined();
 }
 
+JS_DEFINE_NATIVE_FUNCTION(WindowObject::queue_microtask)
+{
+    auto* impl = impl_from(vm, global_object);
+    if (!impl)
+        return {};
+    if (!vm.argument_count()) {
+        vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::BadArgCountAtLeastOne, "queueMicrotask");
+        return {};
+    }
+    auto* callback_object = vm.argument(0).to_object(global_object);
+    if (!callback_object)
+        return {};
+    if (!callback_object->is_function()) {
+        vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotAFunctionNoParam);
+        return {};
+    }
+
+    impl->queue_microtask(static_cast<JS::FunctionObject&>(*callback_object));
+    return JS::js_undefined();
+}
+
 JS_DEFINE_NATIVE_FUNCTION(WindowObject::atob)
 {
     auto* impl = impl_from(vm, global_object);
diff --git a/Userland/Libraries/LibWeb/Bindings/WindowObject.h b/Userland/Libraries/LibWeb/Bindings/WindowObject.h
index b38976d9b6..a148d95ee4 100644
--- a/Userland/Libraries/LibWeb/Bindings/WindowObject.h
+++ b/Userland/Libraries/LibWeb/Bindings/WindowObject.h
@@ -99,6 +99,8 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(get_computed_style);
     JS_DECLARE_NATIVE_FUNCTION(match_media);
 
+    JS_DECLARE_NATIVE_FUNCTION(queue_microtask);
+
 #define __ENUMERATE(attribute, event_name)          \
     JS_DECLARE_NATIVE_FUNCTION(attribute##_getter); \
     JS_DECLARE_NATIVE_FUNCTION(attribute##_setter);