A Node.js script that sends a Growl notification for SEPTA service advisory tweets.

septa-tweet.js

// Include required modules.
var growl = require('growl');
var redis = require('redis');
var http = require('http');
var util = require('util');

// Twitter account name to query.
var twitter_account_name = process.argv[2] || 'SEPTA_WIL';

// Loop interval.
var interval = process.argv[3] || 30000;

// Twitter API path for latest tweet.
var path = '/1/statuses/user_timeline.json?include_entities=false&include_rts=false&trim_user=true&count=1&screen_name=' + twitter_account_name;

// Variable to hold JSON returned from Twitter API.
var latest_tweets = '';

// Create Redis client instance.
client = redis.createClient();

client.on('error', function(err) {
	util.puts('Error: ' + err);
});

client.on('ready', function() {

	setInterval(function() {

		// Get the latest id for a tweet from the specified account.
		client.get('latest', function(err, reply) {

			if (err) {
				util.puts('Error: ' + err);
			} else {

				// If we have the latest id queried, use it in the Twitter API call.
				if (reply) {
					path += '&since_id=' + reply;
				}

				// HTTP client to query the Twitter API.
				var latestTweet = http.createClient(80, 'api.twitter.com');
				var request = latestTweet.request('GET', path, {
					'host' : 'api.twitter.com'
				});
				request.end();
				request.on('response', function(response) {
					response.setEncoding('utf8');
					response.on('data', function(data) {
						latest_tweets += data;
					});
					response.on('end', function() {
						
						// Parse response from the Twitter API.
						var tweets = JSON.parse(latest_tweets);
						
						// Reset variable that holds Twitter API response chuncks.
						latest_tweets = '';
						
						// Enpty array returned.
						if (!tweets.length) {
							util.puts('No new tweets.');
						} else {
							
							// Repeat tweet returned.
							if (tweets[0].id == reply) {
								util.puts('No new tweets.');
							} else {
								
								// Send Growl notification with text of latest Tweet.
								growl.notify('Tweet from @' + twitter_account_name + ': ' + tweets[0].text);
								
								// Update the latest tweet id in redis.
								client.set('latest', tweets[0].id);
							}
						}
					});
				});
			}
		});
	}, interval);
});

Prerequisites:

• Redis installed and running locally. Download here.
• Growlnotify installed and configured with your choice of notification style.

Usage:

~$ node septa-tweet.js

Optionally, pass in the name of a specific SEPTA account you want to watch (default is SEPTA_WIL).

~$ node septa-tweet.js SEPTA_CHW

Optionally, pass in a different interval to check for new tweets (default is 30 seconds).

~$ node septa-tweet.js SEPTA_CHW 60000