JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<div class="container">
    <div class="row">
        <div class="col-xs-4 gray"></div>
        <div class="col-xs-4 green"></div>
        <div class="col-xs-4 gray"></div>
        <div class="col-xs-4 green"></div>
        <div class="col-xs-4 gray"></div>
        <div class="col-xs-4 green"></div>
    </div>
</div>
</body>

CSS

body {
  width: 200px;
  height: auto;
}

.gray {
  background-color: lightgray;
}
.green {
  background-color: lightgreen;
}

JavaScript

var divs = $(".row > div");
var width = divs.width();
divs.height(width)