feat(web): add beforeunload event (#14830)

This commit adds the 'beforeunload' event.

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

3 files changed, 53 insertions, 4 deletions

diff --git a/core/01_core.js b/core/01_core.js
index 9337c0231..156300327 100644
--- a/core/01_core.js
+++ b/core/01_core.js
@@ -267,6 +267,7 @@
     destructureError: opSync.bind(null, "op_destructure_error"),
     terminate: opSync.bind(null, "op_terminate"),
     opNames: opSync.bind(null, "op_op_names"),
+    eventLoopHasMoreWork: opSync.bind(null, "op_event_loop_has_more_work"),
   });
 
   ObjectAssign(globalThis.__bootstrap, { core });
diff --git a/core/ops_builtin_v8.rs b/core/ops_builtin_v8.rs
index 7f0c58212..4bc80faa5 100644
--- a/core/ops_builtin_v8.rs
+++ b/core/ops_builtin_v8.rs
@@ -47,6 +47,7 @@ pub(crate) fn init_builtins_v8() -> Vec<OpDecl> {
     op_op_names::decl(),
     op_apply_source_map::decl(),
     op_set_format_exception_callback::decl(),
+    op_event_loop_has_more_work::decl(),
   ]
 }
 
@@ -786,3 +787,26 @@ fn op_set_format_exception_callback<'a>(
   let old = old.map(|v| v8::Local::new(scope, v));
   Ok(old.map(|v| from_v8(scope, v.into()).unwrap()))
 }
+
+#[op(v8)]
+fn op_event_loop_has_more_work(scope: &mut v8::HandleScope) -> bool {
+  let state_rc = JsRuntime::state(scope);
+  let module_map_rc = JsRuntime::module_map(scope);
+  let state = state_rc.borrow_mut();
+  let module_map = module_map_rc.borrow();
+
+  let has_pending_refed_ops = state.pending_ops.len() > state.unrefed_ops.len();
+  let has_pending_dyn_imports = module_map.has_pending_dynamic_imports();
+  let has_pending_dyn_module_evaluation =
+    !state.pending_dyn_mod_evaluate.is_empty();
+  let has_pending_module_evaluation = state.pending_mod_evaluate.is_some();
+  let has_pending_background_tasks = scope.has_pending_background_tasks();
+  let has_tick_scheduled = state.has_tick_scheduled;
+
+  has_pending_refed_ops
+    || has_pending_dyn_imports
+    || has_pending_dyn_module_evaluation
+    || has_pending_module_evaluation
+    || has_pending_background_tasks
+    || has_tick_scheduled
+}
diff --git a/core/runtime.rs b/core/runtime.rs
index 23fe73013..8b150e4e9 100644
--- a/core/runtime.rs
+++ b/core/runtime.rs
@@ -90,14 +90,14 @@ pub struct JsRuntime {
   event_loop_middlewares: Vec<Box<OpEventLoopFn>>,
 }
 
-struct DynImportModEvaluate {
+pub(crate) struct DynImportModEvaluate {
   load_id: ModuleLoadId,
   module_id: ModuleId,
   promise: v8::Global<v8::Promise>,
   module: v8::Global<v8::Module>,
 }
 
-struct ModEvaluate {
+pub(crate) struct ModEvaluate {
   promise: v8::Global<v8::Promise>,
   sender: oneshot::Sender<Result<(), Error>>,
 }
@@ -158,8 +158,8 @@ pub(crate) struct JsRuntimeState {
   pub(crate) js_wasm_streaming_cb: Option<v8::Global<v8::Function>>,
   pub(crate) pending_promise_exceptions:
     HashMap<v8::Global<v8::Promise>, v8::Global<v8::Value>>,
-  pending_dyn_mod_evaluate: Vec<DynImportModEvaluate>,
-  pending_mod_evaluate: Option<ModEvaluate>,
+  pub(crate) pending_dyn_mod_evaluate: Vec<DynImportModEvaluate>,
+  pub(crate) pending_mod_evaluate: Option<ModEvaluate>,
   /// A counter used to delay our dynamic import deadlock detection by one spin
   /// of the event loop.
   dyn_module_evaluate_idle_counter: u32,
@@ -1021,6 +1021,30 @@ Pending dynamic modules:\n".to_string();
 
     Poll::Pending
   }
+
+  pub fn event_loop_has_work(&mut self) -> bool {
+    let state_rc = Self::state(self.v8_isolate());
+    let module_map_rc = Self::module_map(self.v8_isolate());
+    let state = state_rc.borrow_mut();
+    let module_map = module_map_rc.borrow();
+
+    let has_pending_refed_ops =
+      state.pending_ops.len() > state.unrefed_ops.len();
+    let has_pending_dyn_imports = module_map.has_pending_dynamic_imports();
+    let has_pending_dyn_module_evaluation =
+      !state.pending_dyn_mod_evaluate.is_empty();
+    let has_pending_module_evaluation = state.pending_mod_evaluate.is_some();
+    let has_pending_background_tasks =
+      self.v8_isolate().has_pending_background_tasks();
+    let has_tick_scheduled = state.has_tick_scheduled;
+
+    has_pending_refed_ops
+      || has_pending_dyn_imports
+      || has_pending_dyn_module_evaluation
+      || has_pending_module_evaluation
+      || has_pending_background_tasks
+      || has_tick_scheduled
+  }
 }
 
 extern "C" fn near_heap_limit_callback<F>(