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

This commit adds the 'beforeunload' event.

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

1 files changed, 18 insertions, 0 deletions

diff --git a/runtime/worker.rs b/runtime/worker.rs
index acb50dc30..fd937559f 100644
--- a/runtime/worker.rs
+++ b/runtime/worker.rs
@@ -371,6 +371,24 @@ impl MainWorker {
       "dispatchEvent(new Event('unload'))",
     )
   }
+
+  /// Dispatches "beforeunload" event to the JavaScript runtime. Returns a boolean
+  /// indicating if the event was prevented and thus event loop should continue
+  /// running.
+  pub fn dispatch_beforeunload_event(
+    &mut self,
+    script_name: &str,
+  ) -> Result<bool, AnyError> {
+    let value = self.js_runtime.execute_script(
+      script_name,
+      // NOTE(@bartlomieju): not using `globalThis` here, because user might delete
+      // it. Instead we're using global `dispatchEvent` function which will
+      // used a saved reference to global scope.
+      "dispatchEvent(new Event('beforeunload', { cancelable: true }));",
+    )?;
+    let local_value = value.open(&mut self.js_runtime.handle_scope());
+    Ok(local_value.is_false())
+  }
 }
 
 #[cfg(test)]