var test = {};

for (var key in eventData) {
    key.split('.').reduce(function (lastReturn, prop, index, arr) {
        if (!lastReturn[prop]) {
            if (arr.length - 1 === index) {
                lastReturn[prop] = eventData[key];
            } else {
                lastReturn[prop] = {};
            }
        }
        return lastReturn[prop];
    }, test);
}

for (var key in test) {
    if (key.match(/\[\d+\]/)) {
        var prefix = key.replace(/\[\d+\]/, '');
        test[prefix] = test[prefix] || [];

        if (typeof test[key] === 'object') {
            test[key]
        }

        test[prefix].push(test[key]);
        delete test[key];
    }
}