Add confirmation for closing window (#463)

* Add confirmation for closing window

* Make function an event listener for consistency

* Change let to const

* Refactor for compatability

Author: nol166

packages/ide/src/client.ts

@@ -34,6 +34,12 @@ export abstract class IdeClient {
 		this.loadTime = time(2500);
 
 		let appWindow: Window | undefined;
+
+		window.addEventListener("beforeunload", (e) => {
+			e.preventDefault(); // FireFox
+			e.returnValue = ""; // Chrome
+		});
+
 		window.addEventListener("message", (event) => {
 			if (event.data === "app") {
 				appWindow = event.source as Window;