JSFiddle - React, Tailwind, and code Playground

HTML

<div class="events-list-wrapper">
  <div class="event">
    <p class="date"><span>Jan</span> 17-21</p>
    <h3>Event Title</h3> ...
  </div>
  <div class="event">
    <p class="date"><span>Aug</span> 30-21</p>
    <h3>Event Title</h3> ...
  </div>
</div>

CSS

.past {
  border: 1px solid gray;
}

.today {
  border: 1px solid blue;
}

JavaScript

// get today's date
var today = new Date();
today = new Date(today.getFullYear(), today.getMonth(), today.getDate());

$('div.event').each(function() {
  var div = $(this);
  var divDate = Date.parse($('.date', this).text());
  switch (divDate) {
    case divDate < today:
      div.addClass('past');
      break;
    default:
      div.addClass('today');
      break;
  }
});