1 files changed, 52 insertions, 0 deletions
diff --git a/js/event_target.ts b/js/event_target.ts
new file mode 100644
index 000000000..3226fde96
--- /dev/null
+++ b/js/event_target.ts
@@ -0,0 +1,52 @@
+// Copyright 2018 the Deno authors. All rights reserved. MIT license.
+import * as domTypes from "./dom_types";
+
+/* TODO: This is an incomplete implementation to provide functionality
+ * for Event. A proper spec is still required for a proper Web API.
+ */
+export class EventTarget implements domTypes.EventTarget {
+  public listeners: {
+    [type in string]: domTypes.EventListenerOrEventListenerObject[]
+  } = {};
+
+  public addEventListener(
+    type: string,
+    listener: domTypes.EventListenerOrEventListenerObject | null,
+    options?: boolean | domTypes.AddEventListenerOptions
+  ): void {
+    if (!(type in this.listeners)) {
+      this.listeners[type] = [];
+    }
+    if (listener !== null) {
+      this.listeners[type].push(listener);
+    }
+  }
+
+  public removeEventListener(
+    type: string,
+    callback: domTypes.EventListenerOrEventListenerObject | null,
+    options?: domTypes.EventListenerOptions | boolean
+  ): void {
+    if (type in this.listeners && callback !== null) {
+      this.listeners[type] = this.listeners[type].filter(
+        listener => listener !== callback
+      );
+    }
+  }
+
+  public dispatchEvent(event: domTypes.Event): boolean {
+    if (!(event.type in this.listeners)) {
+      return true;
+    }
+    const stack = this.listeners[event.type].slice();
+
+    for (const stackElement of stack) {
+      if ((stackElement as domTypes.EventListenerObject).handleEvent) {
+        (stackElement as domTypes.EventListenerObject).handleEvent(event);
+      } else {
+        (stackElement as domTypes.EventListener).call(this, event);
+      }
+    }
+    return !event.defaultPrevented;
+  }
+}