nodejs使用require('request')模块发送数据，报错

var request = require('request');request('http://www.baidu.com', function (error, response, body) {    console.log('error:', error); // Print the error if one occurred    console.log('statusCode:', response && response.statusCode); // Print the response status code if a response was received    console.log('body:', body); // Print the HTML for the Google homepage.});

这是官网上的实例，但是我这边报错。error: Error: Invalid protocol: null
不知道什么协议的原因
官方githubrequest