JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="event_id"/>

JavaScript

var events = [];

var new_event = {
    'id': "aze",
    'name': "azee",
    'description': "aze",
    'start_date': "aze",
    'end_date': "aze",
    'participants' : [],
    'pictures' : [],
    'places' : []
};

var new_participant = {
    'id': "sdf",
    'name': "sdf",
    'birthDate': "sdf",
    'pictureUrl': "sdf"
};

events.push(new_event);
events[0].participants.push(new_participant);
console.log(events);