JSFiddle - React, Tailwind, and code Playground

HTML

<div class="myDiv" data-foo="bar"></div>

View browsers console log to see the cache index output

JavaScript

$(function(){
   
    var $myDiv = $(".myDiv");
    $myDiv.data("foo", "baz");
    
    var cacheIndex = $myDiv[0][$.expando];
    
    console.log($.cache[cacheIndex]);
    
});