1 files changed, 46 insertions, 0 deletions
diff --git a/src/js/builtins/EventStream.ts b/src/js/builtins/EventStream.ts
new file mode 100644
index 000000000..c82195eb2
--- /dev/null
+++ b/src/js/builtins/EventStream.ts
@@ -0,0 +1,46 @@
+import type { EventStreamOptions, EventStream as IEventStream } from "bun";
+
+export function getEventStream() {
+  return class EventStream extends ReadableStream implements IEventStream {
+    #ctrl: ReadableStreamDirectController | undefined;
+
+    constructor(opts?: EventStreamOptions) {
+      super({
+        type: "direct",
+        pull: controller => {
+          this.#ctrl = controller;
+          opts?.start?.(this);
+        },
+        cancel: () => {
+          console.log("Cancel!");
+          opts?.cancel?.(this);
+        },
+      });
+    }
+
+    send(event?: unknown, data?: unknown): void {
+      var ctrl = this.#ctrl!;
+      // if (!ctrl) {
+      //   throw new Error("EventStream has ended");
+      // }
+      if (!data) {
+        data = event;
+        event = undefined;
+      } else if (event === "message") {
+        // According to spec, 'The default event type is "message"'
+        // This means we can omit this event type.
+        event = undefined;
+      }
+      if (data === undefined) {
+        throw new TypeError("EventStream.send() requires a data argument");
+      }
+      if (typeof data === "string") {
+        ctrl.write("data: " + data.replace(/\n/g, "\ndata: ") + "\n\n");
+      } else {
+        if (event) ctrl.write("event: " + event + "\n");
+        ctrl.write("data: " + JSON.stringify(data) + "\n\n");
+      }
+      ctrl.flush();
+    }
+  };
+}