JSFiddle - React, Tailwind, and code Playground

HTML

<div class="a1 same-height">Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br>Block 1 <br></div>
<div class="a2 same-height">Block 2</div>

CSS

.a1, .a2{
    display: inline-block;
    vertical-align: top;
    background: #f1f1f1;
}

JavaScript

var heights = $(".same-height").map(function() {
        return $(this).height();
    }).get(),

    maxHeight = Math.max.apply(null, heights);

    $(".same-height").height(maxHeight);