JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="nav">
                                <li class="parent"><a class="nav-top" href="#">Web Design <i class="fa fa-angle-double-down"></i></a>
                                    <ul class="sub-nav">
                                        <li><a class="nav-top" href="#">Self Storage Websites</a></li>
                                        <li><a class="nav-top" href="#">Responsive Websites</a></li>
                                    </ul>
                                </li>
                                <li class="parent"><a class="nav-top" href="#">Internet Marketing <i class="fa fa-angle-double-down"></i></a>
                                    <ul class="sub-nav">
                                        <li><a class="nav-top" href="#">Real SEO</a></li>
                                        <li><a class="nav-top" href="#">PPC (Pay Per Click) Ads</a></li>
                                        <li><a class="nav-top" href="#">Social Media Marketing</a></li>
                                    </ul>
                                </li>
                                <li class="parent"><a class="nav-top" href="hosting.html">Website Hosting</a></li>
                                <li class="parent"><a class="nav-top" href="#">About Us <i class="fa fa-angle-double-down"></i></a>
                                    <ul class="sub-nav">
                                        <li><a class="nav-top" href="#">About EiD</a></li>
                                        <li><a class="nav-top" href="#">Careers</a></li>
                                    </ul>
                                </li>
                                <li class="parent"><a class="nav-top" href="hosting.html">Contact Us</a></li>
                            </ul>

CSS

.sub-nav {
  display: none;
}

JavaScript

$(document).ready(function() {
    $('.parent').click(function() {
        $(".parent").not(this).find(".sub-nav").removeClass('visible').slideUp();
        $(this).find('.sub-nav').toggleClass('visible').slideToggle();
    });
});