JSFiddle - React, Tailwind, and code Playground

HTML

<div class="select">
    <div class="wrapper calcdropdown">
        <a href="#" class="dd-openercalc">Select a calculator</a>
        <a href="#" class="dd-opener pulldown-arrow">&nbsp;</a>
    </div>
    <ul class="selectbox">
        <li>Dropdown item 1</li>
        <li>Dropdown item 2</li>
        <li>Dropdown item 3</li>
    <ul>
</div>
<div class="select">
    <div class="wrapper calcdropdown">
        <a href="#" class="dd-openercalc">Select a calculator</a>
        <a href="#" class="dd-opener pulldown-arrow">&nbsp;</a>
    </div>
    <ul class="selectbox">
        <li>Dropdown item 1</li>
        <li>Dropdown item 2</li>
        <li>Dropdown item 3</li>
    <ul>
</div>
<div class="select">
    <div class="wrapper calcdropdown">
        <a href="#" class="dd-openercalc">Select a calculator</a>
        <a href="#" class="dd-opener pulldown-arrow">&nbsp;</a>
    </div>
    <ul class="selectbox">
        <li>Dropdown item 1</li>
        <li>Dropdown item 2</li>
        <li>Dropdown item 3</li>
    <ul>
</div>

JavaScript

var $j = jQuery.noConflict();
$j(document).ready(function() {
    // hide all the dropdowns by default
    $j(".selectbox").hide();

    $j('.calcdropdown a').live('click',function(e) {
        
        var target=$j(this).parents('.select').children('.selectbox');
            $j('.selectbox').not(target.toggle()).hide();
            e.preventDefault();
    });
});