Read a file line by line in Node.js

gistfile1.js

var fs = require('fs'),
    EventEmitter = require('events').EventEmitter;

var createLineReader = function (filename) {
    var stream = fs.createReadStream(filename),
        em = new EventEmitter(),
        buffer = '';

    stream.on('error', function (error) {
        throw error;
    });

    stream.on('data', function (data) {
        var lines, lineCount, i;

        buffer   += data.toString();
        lines     = buffer.split("\n");
        buffer    = lines.pop();
        lineCount = lines.length;

        for (i = 0; i < lineCount; i++) {
            em.emit('line', lines[i]);
        }
    });

    stream.on('end', function () {
        em.emit('line', buffer);
        em.emit('end');
    });

    return em;
};