Update index.js

Author: Joe Podwys

index.js

@@ -74,7 +74,7 @@ function compression (options) {
 
     // proxy
 
-    res.write = function write (chunk, encoding) {
+    res.write = function write (chunk, encoding, cb){
       if (ended) {
         return false
       }
@@ -84,19 +84,19 @@ function compression (options) {
       }
 
       return stream
-        ? stream.write(new Buffer(chunk, encoding))
-        : _write.call(this, chunk, encoding)
-    }
+        ? stream.write(new Buffer(chunk, encoding), cb)
+        : _write.call(this, chunk, encoding, cb)
+    };
 
-    res.end = function end (chunk, encoding) {
+    res.end = function end (chunk, encoding, cb){
       if (ended) {
         return false
       }
 
       if (!this._header) {
         // estimate the length
-        if (!this.getHeader('Content-Length')) {
-          length = chunkLength(chunk, encoding)
+        if (!this.getHeader('Content-Length'), cb) {
+          length = chunkLength(chunk, encoding, cb)
         }
 
         this._implicitHeader()