Add remux options

src/functions/demux.ts

@@ -10,7 +10,7 @@ enum EventSubscription {
 
 const eventsTarget = {
     close: EventSubscription.Self,
-    data: EventSubscription.All,
+    data: EventSubscription.Self,
     drain: EventSubscription.Self,
     end: EventSubscription.Self,
     error: EventSubscription.Self,
@@ -24,10 +24,14 @@ const eventsTarget = {
 
 type DemuxStreams = NodeJS.WritableStream | NodeJS.ReadWriteStream;
 
+interface DemuxOptions extends WritableOptions {
+    remultiplex?: DemuxStreams;
+}
+
 export function demux(
     construct: (destKey?: string) => DemuxStreams,
     demuxBy: string | ((chunk: any) => string),
-    options?: WritableOptions,
+    options?: DemuxOptions,
 ): Writable {
     return new Demux(construct, demuxBy, options);
 }
@@ -37,18 +41,19 @@ class Demux extends Writable {
     private streamsByKey: {
         [key: string]: DemuxStreams;
     };
-    private destination: Writable;
     private demuxer: (chunk: any) => string;
     private construct: (destKey?: string) => DemuxStreams;
+    private remultiplex?: DemuxStreams;
     constructor(
         construct: (destKey?: string) => DemuxStreams,
         demuxBy: string | ((chunk: any) => string),
-        options: WritableOptions = {},
+        options: DemuxOptions = {},
     ) {
         super(options);
         this.demuxer =
             typeof demuxBy === "string" ? chunk => chunk[demuxBy] : demuxBy;
         this.construct = construct;
+        this.remultiplex = options.remultiplex;
         this.streamsByKey = {};
     }
 
@@ -56,8 +61,10 @@ class Demux extends Writable {
         const destKey = this.demuxer(chunk);
         if (this.streamsByKey[destKey] === undefined) {
             this.streamsByKey[destKey] = await this.construct(destKey);
-            if (this.destination !== undefined) {
-                (this.streamsByKey[destKey] as any).pipe(this.destination);
+            if (this.remultiplex) {
+                (this.streamsByKey[destKey] as NodeJS.ReadWriteStream).pipe(
+                    this.remultiplex,
+                );
             }
         }
 
@@ -70,11 +77,6 @@ class Demux extends Writable {
         }
     }
 
-    public pipe(dest: any) {
-        this.destination = dest;
-        return dest;
-    }
-
     public on(event: string, cb: any) {
         switch (eventsTarget[event]) {
             case EventSubscription.Self: