JSFiddle - React, Tailwind, and code Playground

HTML

<div style="color: red">
    <ul id="container"></ul>
</div>
    <div id="result" ></div>
    <div id="result2" ></div>

JavaScript

var activeFilter = $('<li>BLA</li>');
activeFilter.data('input-id', 'mycustomId');
$("#result").text(activeFilter.data('input-id'));
$('#container').append(activeFilter);

var existing = $('li').filter(function(){return $(this).data('inputId') === "mycustomId"});
$("#result2").text(existing.length);