index.js

var cheerio = require('cheerio');
var request = require('superagent');
var target = 'http://store.apple.com/jp/mac';

var hooks = [
  'https://hooks.slack.com/services/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',
  'https://hooks.slack.com/services/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'
];

var count = 0;

setTimeout(function() {
  var callee = arguments.callee;

  request
    .get(target)
    .end(function(err, res) {
      var $ = cheerio.load(res.text);
      var down = $('[alt="We\'ll be back soon"]').length;
      var soon = $('.macbook-bb-201501 .tagline.fwl').text();
      var released = soon.trim() != 'まもなく登場。';

      var text = released
        ? '新しい MacBook が登場した模様。買うんだ！ :tada: ' + target
        : 'まだ新しい MacBook 出てないっぽい。';

      if (down) text = 'We\'ll back soon.';

      text += ' ' + (new Date()).toString();

      console.log('step', count);
      setTimeout(callee, 1000 * 60);

      if (!released && 0 != count++ % 60) return;

      hooks.forEach(function(hook) {
        request
          .post(hook)
          .send({
            channel: '#canweordermacbookyet',　
            icon_url: 'http://images.apple.com/v/macbook/b/overview/images/overview_usb_macbook_large.jpg',
            username: '新しい MacBook 登場監視するマン',
            text: text
          })
          .end(function(err, res) {
            process.stdout.write('.');
          });
      });
    });
});

package.json

{
  "dependencies": {
    "cheerio": "^0.19.0",
    "superagent": "^1.1.0"
  }
}