Merge pull request #23 from SocketDev/fix-old-browsers

fix for browsers that don't support ?. syntax

Author: feross

lib/transform-stream.js

@@ -7,7 +7,7 @@
  * result.done is a promise that fulfills or rejects once the stream is done.
  * Includes a shim for environments where TransformStream is not available.
  */
-export function transformStream (sourceReadable, transformer) {
+export function transformStream (sourceReadable, transformer = {}) {
   let transformedReadable
   let done
 
@@ -47,7 +47,7 @@ class TransformStreamSource {
   }
 
   async start (controller) {
-    if (this.transformer?.start) {
+    if (this.transformer.start) {
       try {
         await this.transformer.start(controller)
       } catch (err) {
@@ -71,14 +71,14 @@ class TransformStreamSource {
       try {
         const data = await this.reader.read()
         if (data.done) {
-          if (this.transformer?.flush) {
+          if (this.transformer.flush) {
             await this.transformer.flush(controller)
           }
           controller.close()
           this.resolveDone()
           return
         }
-        if (this.transformer?.transform) {
+        if (this.transformer.transform) {
           await this.transformer.transform(data.value, wrappedController)
         } else {
           wrappedController.enqueue(data.value)