JSFiddle - React, Tailwind, and code Playground

HTML

<h3>Is .attr() case sensitive or not?</h3>
<div id="container">
    <select name="someName" id="someId" class="someClass" validationMessage="Testung"></select>
    <a href="#" id="clicker">Check "validationMessage" attribute</a>
</div>
<div id="result"></div>

CSS

*
{
    font-family: sans-serif;
    font-size: 9pt;
}
h3
{
    font-weight: bold;
    font-size: 1.2em;
    margin-bottom: 1em;
}

JavaScript

$("#clicker").click(function(evt){
    evt.preventDefault();
    var sel = $("#someId");
    $("#result").html("validation<u>M</u>essage: '" + sel.attr("validationMessage") + "'<br>validation<u>m</u>essage: '" + sel.attr("validationmessage") + "'<br><u>V</u>ali<u>D</u>ation<u>M</u>essag<u>E</u>: '"+ sel.attr("ValiDationMessagE") + "'");
});