init

app/gulpfile.babel.js/transform.js

@@ -0,0 +1,19 @@
+import { Transform } from 'stream';
+
+export class BufferTransform extends Transform {
+  constructor(transform) {
+    super({
+      objectMode: true,
+      transform(file, enc, callback) {
+        if (file.isBuffer()) {
+          file.contents = Buffer.from(transform(new String(file.contents)));
+        }
+        if (file.isStream()) {
+          console.log('stream file', file.path);
+        }
+        return callback(null, file);
+      },
+    });
+    return this;
+  }
+}