var express = require('express'),
	superagent = require('superagent'),
	cheerio = require('cheerio'),
	async = require('async');

	var app = new express(),
	targetUrl = 'https//cnodejs.org/';

	app.get('/',function(req,res,next){
	async.parallel({
		one:function(callback){
			superagent.get(targetUrl)
				.end(function(err,data){
					if(err) return next(err);

					var $ = cheerio.load(data.text);
					var array1 = [];

					$('#topic_list .topic_title').each(function(index,element){
						var $element = $(element);
						array1.push({
							title:$element.attr('title')
						});
					});
					callback(null,array1);
				});
		},
		two:function(callback){
			superagent.get(targetUrl)
				.end(function(err,data){
					if(err) return next(err);

					var $ = cheerio.load(data.text);
					var array2 = [];

					$('#topic_list .topic_title').each(function(index,element){
						var $element = $(element);
						array2.push({
							href:$element.attr('href')
						});
					});
					callback(null,array2);
				});
		}
	},function(err,result){
		if(err){
			console.log(err);
		}
		var obj = {
			array1:result.array1,
			array2:result.array2
		}
		res.send(obj);
	});
	});

	app.listen(3000,function(){
	console.log('server start...');
	});

错误为 TypeError: Cannot read property ‘request’ of undefined at Request.request (/Users/qianjiahao/crawler/node_modules/superagent/lib/node/index.js:716:27) at Request.end (/Users/qianjiahao/crawler/node_modules/superagent/lib/node/index.js:805:18) at Object.async.parallel.one (/Users/qianjiahao/crawler/app.js:34:6) at /Users/qianjiahao/crawler/node_modules/async/lib/async.js:583:25 at /Users/qianjiahao/crawler/node_modules/async/lib/async.js:125:13 at Array.forEach (native) at _each (/Users/qianjiahao/crawler/node_modules/async/lib/async.js:46:24) at Object.async.each (/Users/qianjiahao/crawler/node_modules/async/lib/async.js:124:9) at _parallel (/Users/qianjiahao/crawler/node_modules/async/lib/async.js:582:20) at Object.async.parallel (/Users/qianjiahao/crawler/node_modules/async/lib/async.js:598:9)

谁能指点一下，第一次用async，不太熟悉，谢谢。