JSFiddle - React, Tailwind, and code Playground

HTML

<div class="fillColor1"></div>
<div class="fillColor2"></div><br/>
<button>Click me</button>

CSS

.fillColor1 {
    background: black;
    height: 0;
    margin-left: 24px;
    position: relative;
    width: 3px;
}

.fillColor2 {
    background: black;
    height: 0;
    margin-left: 41px;
    position: relative;
    width: 3px;
}

JavaScript

function fx(elem, callback) {
     alert('called ' + elem[0]);
     $('.fillColor' + elem[0])
     .animate({
         height: '50px'
     }, 600, function() {
       elem.splice(0, 1);
       callback.call($, elem)
     });
};
/*
function second() {
    alert('called second');
    $('.fillColor2').animate({
         height: '50px'
     }, 600);
}
*/
$('button').click(function() {
    fx.call($, [1, 2], fx);    
});