Add flush method

packages/node/src/app/analytics-node.ts

@@ -69,6 +69,14 @@ export class Analytics extends NodeEmitter implements CoreAnalytics {
     return version
   }
 
+  /**
+   * Instantly flush any queued events, if there are any.
+   * @returns a promise resolving after the batch request has been successfully sent.
+   */
+  public flush(): Promise<void> {
+    return this._publisher.flush()
+  }
+
   /**
    * Call this method to stop collecting new events and flush all existing events.
    * This method also waits for any event method-specific callbacks to be triggered,

packages/node/src/plugins/customerio/publisher.ts

@@ -12,7 +12,7 @@ function sleep(timeoutInMs: number): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, timeoutInMs))
 }
 
-function noop() { }
+function noop() {}
 
 interface PendingItem {
   resolver: (ctx: Context) => void
@@ -89,6 +89,23 @@ export class Publisher {
     this._batch = undefined
   }
 
+  /**
+   * Instantly flush any queued events, if there are any.
+   * @returns a promise resolving after the batch request has been successfully sent.
+   */
+  async flush(): Promise<void> {
+    const batch = this._batch
+
+    if (!batch || batch.length === 0) {
+      return
+    }
+
+    const resultPromise = this.send(batch)
+    this.clearBatch()
+    // If the send request fails, the caller will throw when "awaiting" this returned promise
+    return resultPromise
+  }
+
   flushAfterClose(pendingItemsCount: number) {
     if (!pendingItemsCount) {
       // if number of pending items is 0, there will never be anything else entering the batch, since the app is closed.