[fix] make more functional

Author: jcrugzz

Diff for: lib/http-proxy/passes/ws-incoming.js

@@ -1,6 +1,5 @@
 var http   = require('http'),
     https  = require('https'),
-    util   = require('util'),
     common = require('../common'),
     passes = exports;
 
@@ -114,24 +113,27 @@ var passes = exports;
 
       if (proxyHead && proxyHead.length) proxySocket.unshift(proxyHead);
 
-      var writeHead = [
-        'HTTP/1.1 101 Switching Protocols'
-      ];
-
-      for(var i in proxyRes.headers) {
-          if (util.isArray(proxyRes.headers[i])) {
-            var a   = proxyRes.headers[i];
-            var len = a.length;
-
-            for (var x = 0; x < len; x++) {
-              writeHead.push(i + ": " + a[x]);
-            }
-        } else {
-          writeHead.push(i + ": " + proxyRes.headers[i]);
-        }
-      }
+      //
+      // Remark: Handle writing the headers to the socket when switching protocols
+      // Also handles when a header is an array
+      //
+      socket.write(
+        Object.keys(proxyRes.headers).reduce(function (head, key) {
+          var value = proxyRes.headers[key];
+
+          if (!Array.isArray(value)) {
+            head.push(key + ': ' + value);
+            return head;
+          }
+
+          for (var i = 0; i < value.length; i++) {
+            head.push(key + ': ' + value[i]);
+          }
+          return head;
+        }, ['HTTP/1.1 101 Switching Protocols'])
+        .join('\r\n') + '\r\n\r\n'
+      );
 
-      socket.write(writeHead.join('\r\n') + '\r\n\r\n');
       proxySocket.pipe(socket).pipe(proxySocket);
 
       server.emit('open', proxySocket);