/*写文件、追加写、读文件*/

var fs = require('fs');

function wrapper(fn,context) {

    var args = Array.prototype.slice.call(arguments,2);

    return new Promise((resolve,reject) => {

        args.push((err,data) => {

            err ? reject(err) : resolve(data);

        });

        fn.apply(context,args);

    });

}

wrapper(fs.writeFile,fs,'message.txt','word')

    .then(() => wrapper(fs.appendFile,fs,'message.txt','word'))

    .then(() => wrapper(fs.readFile,fs,'message.txt','word'))

    .then(data => console.log(data))

    .catch(err => console.log(err));

/*获取员工id、并发获取两个接口信息、读信息*/

var http = require('http');

var url = require('url');

function delayPromise(ms) {

    return new Promise((resolve,reject) => {

        setTimeout(reject, ms);

    });

}

function get(url,ms) {

    return new Promise.race([

        delayPromise(ms),

        wrapper(request,null,url).then(data => {

            return JSON.parse(data);

        })

    ]);

}

get('http://demos.so/result/homework.promise.userInfo')

    .then( data => {

        return Promise.all([get('http://demos.so/result/userid=' + args['_id']), get('http://demos.so/result/student=' + args['_id'])])

    }

    .then( data => console.log(data))

    .catch( err => console.log(args));