countpauses.js

var fs = require('fs');
var readline = require('readline');

var log = [];

// Set up to read the log line by line
var rd = readline.createInterface({
    input: fs.createReadStream('./gtx-edx-events-2016-07-11.log'),
    output: process.stdout,
    terminal: false
});

// Parse each line as JSON
rd.on('line', function(line) {
    log.push(JSON.parse(line));
});

// When we have all the lines parsed we can start querying them
rd.on('close', function() {
    var matches = 0;

    // Check each line for matches
    for(var i = 0; i < log.length; i++) {

        // Particular user pauses a video
        if (log[i].username === 'malekmalke' && log[i].event_type === 'pause_video') {
            matches++;
        }
    }

    console.log(matches);
});