JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//ajax.googleapis.com/ajax/libs/jqueryui/1.10.4/jquery-ui.min.js"></script>
<link rel="stylesheet" href="//ajax.googleapis.com/ajax/libs/jqueryui/1.10.4/themes/smoothness/jquery-ui.css">
<input type="hidden" class="test" value="0" />
<a class="addition-input">Click me</a>

CSS

.selected {
        font-weight:bold;
    }
    * {
        user-select:none;
        -webkit-user-select:none;
    }

JavaScript

$('a.addition-input').click(function (event) {
    event.preventDefault();
    console.log($('input.test').val());
    var currentValue = parseFloat($('input.test').val());
    var step = 0.5;
    var newValue = currentValue + step;

    $('input.test').val(newValue);
    console.log(newValue);
});