JSFiddle - React, Tailwind, and code Playground

HTML

<div>Not match</div>
<div>Foobar</div>
<div>foobar</div>
<div>not matched</div>

JavaScript

$.expr[":"].containsNoCase = $.expr.createPseudo(function(arg) {
    return function( elem ) {
        return $(elem).text().toUpperCase().indexOf(arg.toUpperCase()) >= 0;
    };
});

$("div:contains('foo')").css("color", "#0000ff");
$("div:containsNoCase('foo')").css("background-color", "#dddddd");