crawler.js

var http = require('http');
var url = require('url');
var fs = require('fs');
var path = require('path');

/*var targetURL = process.argv[2] || null;*/
var targetURL = 'http://www.stust.edu.tw/';


if (!targetURL) {
    process.exit();
}

//解析URL
var urlObj = url.parse(targetURL);


var req = http.request({
    hostname: urlObj.hostname,
    path: urlObj.path,
    method: 'GET'
}, function (res) {

    //解析網址路徑，並取得檔案名稱
    var filename = path.basename(urlObj.path);

    //判斷檔案是否存在
    fs.exists(filename, function (exists) {

        if (exists) {

            fs.unlink(filename, function (err) {
                if (err)
                    console.log(err);
                saveFile();
            });

            return;
        }

        saveFile();
    });

    function saveFile() {

        //收到資料
        res.on('data', function (chunk) {

            console.log('Downloading');
            fs.appendFile(filename, chunk, function () {

                res.on('end', function (chunk) {

                    console.log('Finished');
                    process.exit();
                });
            });
        });
    }

});

error.js

events.js:85
      throw er; // Unhandled 'error' event
            ^
Error: read ECONNRESET
    at exports._errnoException (util.js:746:11)
    at TCP.onread (net.js:559:26)