var request = require('request');
var xml2js = require('xml2js');
var url = 'http://blog.whyun.com/feed.xml';
var keyword = '异步';
function parseResponse(url,description, error,response,body,callback) {
    if (error) {
        console.error('请求'+url+'失败',error);
        callback('请求'+description+'网络错误');
        return;
    }
    if (!response) {
        callback('请求'+description+'失败，未知错误');
        return;
    }
    if (response.statusCode != 200) {
        console.error(url, response.statusCode, body);
        callback('请求'+description+'失败['+response.statusCode+']');
        return;
    }
    xml2js.parseString(body,{explicitRoot:false,explicitArray : false},function(err,data) {
        if (err) {
            console.error('解析返回数据失败',err,body);
            return callback('解析返回数据失败');
        }
        callback(false,data);
    });
}
request({
    url:url,
    headers:{'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36'}
},function(error,response,body) {
    parseResponse(url,'解析xml',error,response,body,function(err,data){
        if (err) {
            return;
        }
        
        if (!data || !data.channel || !data.channel.item) {
            return console.error('数据非法',data);
        }
        var articles = data.channel.item.filter(function(item) {
            return item.title && item.title.indexOf(keyword) !== -1;
        }); 
        console.log(articles);
    });
});