JSFiddle - React, Tailwind, and code Playground

HTML

<div id="first">
  <div id="source-AAA"></div>
  <div class='dany targ' id="source-CCC"></div>
  <div id="source-EEE"></div>
  <div class='visy targ' id="source-FFF"></div>
</div>
<div id="second">
  <div id="BBB"></div>
  <div id="CCC"></div>
  <div id="DDD"></div>
  <div id="FFF"></div>
</div>

CSS

div > div {
    height: 30px;
    width: 100px;
    background: #aaa;
    margin-bottom: 10px;
}

.targ {
    background: #FF0000;
}

JavaScript

var divsToSelect = [];

$('#first div').each(function(){
    divsToSelect.push( $(this).attr('id').substr(-3) );
});

$('#' + divsToSelect.join(',#')).css('background', 'green');

$('.dany, .targ').css('background', 'blue');