Scans for networks within the area and sends the number of networks it sees over an I2C connection

main.js

var i2c = require('i2c');
var sudo = require("sudo");
var address = 0x04;					//FLORA Board device address
var wire = new i2c(address, {device: '/dev/i2c-1'});	//Begin I2C connection with FLORA board

//Scan networks every 5 seconds
setInterval(ScanForNetwork, 5 * 1000);

function ScanForNetwork() {
	iwlistScan(function(err, results){
		//Print out results of scan
		console.log(results);
		//Write to FLORA how many devices we saw
		wire.writeByte(results.length, function(err) {
			console.log("Error: " + err);
		});
	});
}

//maxogden's scan call from https://github.com/maxogden/iwlist/blob/master/index.js
//modified so that it uses sudo calls with elevated privileges 
function iwlistScan(callback) {
	var ps = sudo(['iwlist', 'wlan0', 'scan']);
	var line = '';
	ps.stdout.on('data', function ondata(buf) {
		for(var i = 0; i < buf.length; i++) {
			if(buf[i] === 10) {
				parseLine(line);
				line = '';
			}
			else line += String.fromCharCode(buf[i]);
		}
	});
	var stderr = '';
	ps.stderr.on('data', function (buf) {stderr += buf });
	ps.on('close', function() {
		if (code !== 0) return callback('Code = ' + stderr);
		ap.sort(function(a, b) {
			var x = a['signal']; var y = b['signal'];
			return ((x < y) ? -1 : ((x > y) ? 1 : 0));
		}).reverse();
		callback(null, ap);
	});
	var code;
	ps.on('exit', function(c) {
		code = c;
	});

	var ap = [];
	var current = null;
	function parseLine(line) {
		var m;
		if(m = /^\s+Cell \d+ - Address: (\S+)/.exec(line)) {
			current = {address : m[1] };
			ap.push(current);
			return;
		}
		if(!current) return;
		if(m = /^\s+ESSID:"(.+)"/.exec(line)) {
			current.essid = m[1];
		}
		if(m = /^\s+Encryption key:(.+)/.exec(line)) {
			current.encrypted = m[1] !== 'off';
		}
		if(m = /^\s+ESSID:(.+?)\//.exec(line)) {
			current.signal = +m[1];
		}
	}
}