JSFiddle - React, Tailwind, and code Playground

HTML

<div id="eventCheck"></div>

JavaScript

// ----------------------------------------------------//
// Todays date
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yyyy = today.getFullYear();

// Add Zero if it number is between 0-9
if(dd<10) {
    dd = '0'+dd;
}
if(mm<10) {
    mm = '0'+mm;
}

var today = yyyy + '' + mm + '' + dd ;


// ----------------------------------------------------//
// Day of event
var endDay = 15; // day 15
var endMonth = 01; // month 01 (January)
var endYear = 2017; // year 2017

// Add Zero if it number is between 0-9
if(endDay<10) {
    endDay = '0'+endDay;
} 
if(endMonth<10) {
    endMonth = '0'+endMonth;
}

// eventDay - date of the event
var eventDay = endYear + '/' + endMonth + '/' + endDay;
// ----------------------------------------------------//



// ----------------------------------------------------//
// check if eventDay has been or not
if ( eventDay < today ) {
	document.getElementById('eventCheck').innerHTML += 'Date has passed (event is over)';  // true
} else {
	document.getElementById('eventCheck').innerHTML += 'Date has not passed (upcoming event)'; // false
}