Check Event constructor params (denoland#1997)

js/event.ts

@@ -1,6 +1,6 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import * as domTypes from "./dom_types";
-import { getPrivateValue } from "./util";
+import { getPrivateValue, requiredArguments } from "./util";
 
 // WeakMaps are recommended for private attributes (see MDN link below)
 // https://developer.mozilla.org/en-US/docs/Archive/Add-ons/Add-on_SDK/Guides/Contributor_s_Guide/Private_Properties#Using_WeakMaps
@@ -31,6 +31,8 @@ export class Event implements domTypes.Event {
  private _path: domTypes.EventPath[] = [];
 
  constructor(type: string, eventInitDict: domTypes.EventInit = {}) {
+ requiredArguments("Event", arguments.length, 1);
+ type = String(type);
  this._initializedFlag = true;
  eventAttributes.set(this, {
  type,

js/event_test.ts

@@ -68,3 +68,15 @@ test(function eventPreventDefaultSuccess() {
  cancelableEvent.preventDefault();
  assertEquals(cancelableEvent.defaultPrevented, true);
 });
+
+test(function eventInitializedWithNonStringType() {
+ const type = undefined;
+ const event = new Event(type);
+
+ assertEquals(event.isTrusted, false);
+ assertEquals(event.target, null);
+ assertEquals(event.currentTarget, null);
+ assertEquals(event.type, "undefined");
+ assertEquals(event.bubbles, false);
+ assertEquals(event.cancelable, false);
+});