Merge pull request #7 from thorikawa/fix-port-on-is-not-a-function

Fix "this.port.on is not a function" error while connecting to the device.

Author: lsongdev

example/index.js

@@ -23,7 +23,9 @@ device
         console.log('received message:', buffer.toString());
       });
 
-      connection.write(new Buffer('Hello!', 'utf-8'));
+      connection.write(new Buffer('Hello!', 'utf-8'), () => {
+        console.log('wrote');
+      });
     });
 
   });

index.js

@@ -18,14 +18,18 @@ function Connection(port, address){
   const self = this;
   this.port    = port;
   this.address = address;
-  this.port.on('data', function(buffer){
-    if(buffer.length > 0){
-      self.port.read(function(err, data){
-        if(err) return self.emit('error', err);
-        self.emit('data', data);
-      });
-    }
-  });
+  const read = function () {
+    process.nextTick(function() {
+      if (self.isOpen()) {
+        self.port.read(function(err, data){
+          if(err) return self.emit('error', err);
+          self.emit('data', data);
+          read();
+        });
+      }
+    });
+  }
+  read();
 };
 /**
  * [write description]
@@ -44,9 +48,14 @@ Connection.prototype.write = function(data, callback){
  */
 Connection.prototype.close = function(callback){
   this.port.close(callback);
+  this.port = undefined;
   return this;
 };
 
+Connection.prototype.isOpen = function(callback){
+  return this.port !== undefined;
+};
+
 /**
  * [inherits description]
  * @param  {[type]} target [description]