access_log count group by user agent

script.js

var fs = require('fs');
var UAParser = require('ua-parser-js');
var parser = new UAParser();
var map = [];

function readLines(input, func) {
  var remaining = '';
 
  input.on('data', function(data) {
    remaining += data;
    var index = remaining.indexOf('\n');
    while (index > -1) {
      var line = remaining.substring(0, index);
      remaining = remaining.substring(index + 1);
      func(line);
      index = remaining.indexOf('\n');
    }
  });
 
  input.on('end', function() {
    if (remaining.length > 0) {
      func(remaining);
    }
	printOutput();
  });
}

function parseLine(line) {
	var arr = line.split('"');
	var userAgent = arr[5].trim();
	var res = parser.setUA(userAgent).getResult();
	var key = res.browser.name + "|" + res.browser.version+"|" + res.os.name+"|" + res.os.version;
	var tot = map[key];
	if(tot == undefined)
	  tot = 0;
	tot = parseInt(tot) + 1;
	map[key] = tot;
}

function printOutput(){
	console.log("num|browser name|browser version|OS name|OS version");
	for (var i in map) {
		console.log( map[i]+ "|" +i);
	}
}

var input = fs.createReadStream(process.argv[2]);

readLines(input, parseLine);