部分適用メソッドを使って遅延評価

gistfile1.js

// 部分適用メソッド
if (! Function.prototype.papply) {
    Function.prototype.papply = function (thisObject, args) {
        var slice = Array.prototype.slice;
        var func  = this;
        return function () {
            args = args.concat(slice.apply(arguments));
            return func.apply(thisObject, args);
        };
    };
}

// startメソッドの引数の関数を順番に実行していく
// 次の関数を実行するタイミングは、release メソッドが呼ばれた時
function Queue (startDelay) {
    this.works;
    this.startDelay = startDelay || 0;
}
(function () {
    Queue.prototype = {
        start: function () {
            this.works = Array.prototype.slice.apply(arguments);
            if (! this.startDelay) return this.release();
        },
        release: function (f) {
            var func, result;
            if (f && typeof f === 'function') result = f();
            if (this.works && this.works.length > 0) {
                func = this.works.shift();
                return func(); //func(result);
            }
        }
    };
})();

var http = require('http'),
    url  = require('url');
;
function HTTPClient (config) {
    config = config || {};
    this['redirectOk'] = config['redirectOk'] || false;
    this['cookie']     = config['cookie'];
    this['referer']    = config['referer'];
}
(function () {
    HTTPClient.prototype.request = function (/* method, uriStr, headers, body, callback */) {
        var args = Array.prototype.slice.apply(arguments),
            method   = args.shift().toUpperCase(),
            uriStr   = args.shift(),
            callback = args.pop(),
            headers  = args.shift() || {},
            body     = args.shift() || null,
            uri, options, path, req, that
        ;

        if (typeof uriStr === 'function') uriStr = uriStr();

        uri  = url.parse(uriStr);
        path = (! uri['pathname'])                   ? '/' :
               (uri['pathname'].slice(0, 1) === '/') ? uri['pathname']
                                                     : [ '/', uri['pathname'] ].join('');

        if (method === 'POST') {
            headers['content-length'] = (body) ? body.length : 0;
            if (! headers['content-type']) headers['content-type'] = 'application/x-www-form-urlencoded';
        }

        if (! headers['referer'] && this['referer']) headers['referer'] = this['referer'];
        if (! headers['cookie']  && this['cookie'] ) headers['cookie']  = this['cookie'];

        options = {
            "method" : method,
            "host"   : uri['hostname'],
            "port"   : (uri['port']) ? uri['port'] : (uri['protocol'] === 'https') ? '443' : '80',
            "path"   : [ path, uri['search'] ].join(''),
            "headers": headers
        };

        req = http.request(options);
        if (method === 'POST') req.write(body);
        req.end();

        that = this;
        req.on('error', function (e) {
            console.log([ e.name, e.message ].join(': '));
        });
        req.on('response', function (res) {
            var statusCode = res.statusCode, _location, _headers;

            that['referer'] = uriStr;
            if (res.headers['set-cookie']) that['cookie'] = res.headers['set-cookie'][0];

            if (that['redirectOk'] && statusCode >= 300 && statusCode < 400 && res.headers['location']) {
                _location = res.headers['location'];
                _headers  = { 'referer' : uriStr };
                if (that['cookie']) _headers['cookie'] = that['cookie'];
                //console.log('redirect >> ' + _location);
                that.request('GET', _location /* , _headers */, function (_response) {
                    callback(_response, [ _location, _headers, null]);
                });
            } else {
                callback(res, [ uriStr, headers, body ]);
            }
        });
    };

})();

var queue  = new Queue;
var client = new HTTPClient({ redirectOk : true });
var myData = {};

var body = 'mode=login&pixiv_id=xxx&pass=xyz';
var illust_id = '22134239';

var wwwPixivNet = 'http://www.pixiv.net';
var loginPhp    = [ wwwPixivNet, '/login.php' ].join('');
var illustTop   = [ wwwPixivNet, '/member_illust.php?mode=medium&illust_id=', illust_id ].join('');

queue.start(
        client.request.papply(client, [ 'POST', loginPhp, {}, body, function (res, req) {
                queue.release(report.papply(null, [ res, req ]));
        } ]),
/*
        client.request.papply(client, ['GET', [ wwwPixivNet, '/mypage.php' ].join(''), function (res, req) {
                report(res, req);
                queue.release();
        } ]),
*/
        client.request.papply(client, [ 'GET', illustTop, function (res, req) {
                report(res,req);
                var data = '';
                res.setEncoding('utf-8');
                res.on('data', function (chunk) { data += chunk; });
                res.on('end', function () {
                        data = data.replace(/\n/g, '');
                        var reg = /<a href="(member_illust\.php\?mode=[^"]+?)"[^>]+?><img src="([^"]+?)".+?title="([^"]+?)"/;
                        var result = reg.exec(data);
                        myData['illustBig'] = [ wwwPixivNet, result[1].replace(/&amp;/g, "&") ].join('/');
                        console.log(myData['illustBig']);
                        queue.release();
                });
        } ]),

        client.request.papply(client, [ 'GET', function () { return myData['illustBig']; }, function (res, req) {
                report(res,req);
                var data = '';
                res.setEncoding('utf-8');
                res.on('data', function (chunk) { data += chunk; });
                res.on('end', function () {
                        data = data.replace(/\n/g, '');
                        var reg = /<img src="(http:\/\/img\d{2,3}[^"]+?)"/;
                        var result = reg.exec(data);
                        myData['imgSrc'] = result[1];
                        console.log(myData['imgSrc']);
                        queue.release();
                });
        } ]),

        client.request.papply(client, [ 'GET', function () { return myData['imgSrc']; }, function (res, req) {
                report(res,req);
                var imgSrc = myData['imgSrc'];
                var target = require('path').basename(imgSrc);
                console.log(imgSrc + " >> " + target);
                var writeStream = require('fs').createWriteStream(target);
                writeStream.on('error', function (exception) {
                        throw exception;
                });
                writeStream.on('close', function () {
                        console.log('writeStream say "close"');
                });

                res.on('data', function (chunk) {
                        writeStream.write(chunk);
                });
                res.on('end', function () {
                        writeStream.end();
                        console.log('response say "end"');
                });
        } ])
);


function report(res, req) {
    console.log([ "Response-statusCode", res.statusCode ].join(': '));
    console.log([ "Response-headers",    JSON.stringify(res.headers) ].join(': '));
    console.log([ "Request-uri",         req[0] ].join(': '));
    console.log([ "Request-headers",     JSON.stringify(req[1]) ].join(': '));
    console.log([ "Request-body",        req[2] ].join(': '));
    console.log('');
}

1;

Function.bind が使える場面だったら、そっちを使う

function sum () {
    return [].reduce.apply(arguments, [ function (a, b) { return a + b; }, 0 ]);
}

var keihi = sum.bind(null, 250, 350); // 'null' には thisObj が入る
console.log(keihi()); // 600

var amount = keihi(630, 772, 525);
console.log(amount); // 2527