JSFiddle - React, Tailwind, and code Playground

HTML

<button class="follow_btn btn btn-success" value="1">Follow</button>

CSS

.btn {
    padding:1em;
}
.btn-success {
    background:green;
}
.btn-danger {
    background:red;
}

JavaScript

$(document).on("click", '.follow_btn', function () {
    var this_btn = $(this);
    this_btn.removeClass("btn-success follow_btn").addClass("btn-danger unfollow_btn");
});

$(document).on("click", '.unfollow_btn', function () {
    var this_btn = $(this);
    this_btn.removeClass("btn-danger unfollow_btn").addClass("btn-success follow_btn");
});