WMATA NextBus script

nextbus.js

#!/usr/bin/env node
/**
 * Gets the number of minutes before a bus shows up at a particular bus stop.
 *
 * Usage: ./nextbus.js API-KEY STOP-ID
 */

// Since WMATA uses Mashery you need to get a Mashery account, and then register
// your application. See http://developer.wmata.com/
var apiKey = process.argv[2];

// WMATA has an ID for every stop. You can get these off the stops themselves or
// get them from http://www.wmata.com/nextbus
var stopId = process.argv[3];

var opts = {
    host: 'api.wmata.com',
    path: '/NextBusService.svc/json/JPredictions?StopID='+ stopId +'&api_key='+ apiKey
};

var http = require('http');
http.get(opts, function(res) {
    if (res.statusCode != 200) {
        console.warn('Got %d from wmata', res.statusCode);
        process.exit(1);
    }

    var data = '';
    res.on('data', function (chunk) {
        data += chunk;
    });
    res.on('end', function() {
        data = JSON.parse(data);
        if (data.Predictions.length) {
            console.log(data.Predictions[0].Minutes);
        }
        else {
            console.log('No approaching vehicles.');
        }
    });
}).on('error', function(err){
    console.warn(err)
    process.exit(1)
});