JSFiddle - React, Tailwind, and code Playground

HTML

<h1>
Hello
</h1>
<p class="active">
  hello
</p>
<h1>
Goodbye
</h1>
<p>
  Goodbye
</p>

CSS

p {
  opacity: 0;
}

.active {
  opacity: 1 !important;
}

JavaScript

function classChange() {
    if($(this).hasClass('active')) {
        //do nothing
    }
    else {
        $('.active').removeClass('active');
        $(this).next('p').addClass('active');
    }
}

$('h1').click(function() {
	classChange();
});