JSFiddle - React, Tailwind, and code Playground

HTML

<a href="test" class="test">Hello</a>
<br />
<a href="test" class="test">Hello</a>

JavaScript

$.fn.test = function(str) {
    this.each(function() {
        $(this).data('test', true);
        alert(str);
    });
};

$.fn.pluginApplied = function(pluginName) {
    var count = 0;
    this.each(function() {
        if($(this).data(pluginName)) {
            count++;
        }
    });
    return count;
};

$("a").test('test');
    
alert($("*").pluginApplied('test'));