如何修改nodejs代理

Question

我使用了代理 - https://github.com/pkrumins/nodejs-proxy。优秀的工作，但我需要修改响应数据到客户端，所以如果我更改代码（代码片段）：

proxy_request.addListener('response', function(proxy_response) {

if(legacy_http && proxy_response.headers['transfer-encoding'] != undefined){
    console.log("legacy HTTP: "+request.httpVersion);

    //filter headers
    var headers = proxy_response.headers;
    delete proxy_response.headers['transfer-encoding'];        
    var buffer = "";

    //buffer answer
    proxy_response.addListener('data', function(chunk) {
      buffer += chunk;
    });
    proxy_response.addListener('end', function() {
      headers['Content-length'] = buffer.length;//cancel transfer encoding "chunked"
      response.writeHead(proxy_response.statusCode, headers);
      response.write(buffer, 'binary');
      response.end();
    });
} else {

    proxy_response.process = function(chunk){
      proxy_response.buf = "";
      chunk = this.buf + chunk; 
      chunk = chunk.replace('</body>', "my html here</body>"); 
      response.write(chunk, 'binary');
    };
    //easy data forward
    proxy_response.addListener('data', function(chunk) {

      response.write(chunk, 'binary');
    });
    proxy_response.addListener('end', function() {
      response.end();
    });
    //send headers as received
    //response.writeHead(proxy_response.statusCode, proxy_response.headers);
}
});

但是这段代码不起作用。有人可以帮我修改数据吗？感谢。