perf: make the most of streamed rendering

src/emitters/emitter.ts

@@ -1,4 +1,11 @@
 export interface Emitter {
+  /**
+   * Write a html value into emitter
+   * @param html string, Drop or other primitive value
+   */
   write (html: any): void;
-  end (): void;
+  /**
+   * Buffered string
+   */
+  buffer: string;
 }