JSFiddle - React, Tailwind, and code Playground

HTML

<div class="bouncer"></div>
<div class="results"></div>

CSS

.bouncer {
    position: absolute;
    width: 50px;
    height: 50px;
    background-color: red;
}

.results {
    float: right;
}

JavaScript

function loop() {
    $('.bouncer').animate({'top': '500'}, {
        duration: 1000, 
        complete: function() {
            $('.bouncer').animate({top: 0}, {
                duration: 1000, 
                complete: loop});
        }});
    
    $('<div/>').text('exiting loop').appendTo($('.results'));
}
loop();