JSFiddle - React, Tailwind, and code Playground

HTML

<div class="focus_col" data-id="1">COL1</div>
  <div class="focus_hidden" data-id="1">HIDDEN1</div>
  <div class="focus_col" data-id="2">COL2</div>
  <div class="focus_hidden" data-id="2">HIDDEN2</div>

JavaScript

$('.focus_hidden').hide();
$('.focus_col').mouseover(function() {
    $("*[data-id="+$(this).data('id')+"]").show();
  return false;
});
$('.focus_col').mouseout(function() {
    $("*[data-id="+$(this).data('id')+"]").hide();
  return false;
});