refactor: Event and EventTarget implementations (#4707)

Refactors Event and EventTarget so that they better encapsulate their
non-public data as well as are more forward compatible with things like
DOM Nodes.

Moves `dom_types.ts` -> `dom_types.d.ts` which was always the intention,
it was a legacy of when we used to build the types from the code and the
limitations of the compiler.  There was a lot of cruft in `dom_types`
which shouldn't have been there, and mis-alignment to the DOM standards.
This generally has been eliminated, though we still have some minor
differences from the DOM (like the removal of some deprecated
methods/properties).

Adds `DOMException`.  Strictly it shouldn't inherit from `Error`, but
most browsers provide a stack trace when one is thrown, so the behaviour
in Deno actually better matches the browser.

`Event` still doesn't log to console like it does in the browser.  I
 wanted to get this raised and that could be an enhancement later on (it
 currently doesn't either).

1 files changed, 12 insertions, 28 deletions

diff --git a/cli/js/web/custom_event.ts b/cli/js/web/custom_event.ts
index 418b7ea34..ea76d2c94 100644
--- a/cli/js/web/custom_event.ts
+++ b/cli/js/web/custom_event.ts
@@ -1,44 +1,28 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
-import * as domTypes from "./dom_types.ts";
-import * as event from "./event.ts";
+import { EventImpl as Event } from "./event.ts";
 import { requiredArguments } from "./util.ts";
 
-export class CustomEvent extends event.Event implements domTypes.CustomEvent {
-  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  #detail: any;
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export class CustomEventImpl<T = any> extends Event implements CustomEvent {
+  #detail: T;
 
-  constructor(
-    type: string,
-    customEventInitDict: domTypes.CustomEventInit = {}
-  ) {
-    super(type, customEventInitDict);
+  constructor(type: string, eventInitDict: CustomEventInit<T> = {}) {
+    super(type, eventInitDict);
     requiredArguments("CustomEvent", arguments.length, 1);
-    const { detail = null } = customEventInitDict;
-    this.#detail = detail;
+    const { detail } = eventInitDict;
+    this.#detail = detail as T;
   }
 
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  get detail(): any {
+  get detail(): T {
     return this.#detail;
   }
 
-  initCustomEvent(
-    _type: string,
-    _bubbles?: boolean,
-    _cancelable?: boolean,
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    detail?: any
-  ): void {
-    if (this.dispatched) {
-      return;
-    }
-
-    this.#detail = detail;
-  }
-
   get [Symbol.toStringTag](): string {
     return "CustomEvent";
   }
 }
 
-Reflect.defineProperty(CustomEvent.prototype, "detail", { enumerable: true });
+Reflect.defineProperty(CustomEventImpl.prototype, "detail", {
+  enumerable: true,
+});