JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="mainmenu_ul">
    <li id="mainmenu1"> <a data-badge="1" href="javascript:void(0)"><i>Menu1</i></a></li>
    <li id="mainmenu2"> <a data-badge="2" href="javascript:void(0)"><i>Menu2</i></a></li>
    <li id="mainmenu3"> <a data-badge="5" href="javascript:void(0)"><i>Menu3</i></a></li>
</ul>

<br/>
<br/>
<a href="javascript:void(0);" onClick="change();">Change it to 444</a>

CSS

[data-badge] {
    position: relative;
}
/* line 197, /Users/bram/Dropbox/Apps/Spina 2/source/stylesheets/buttons.sass */
[data-badge]:after {
    border: 1px solid #660000;
    color: white;
    content: attr(data-badge);
    font-family:"Century Gothic";
    font-weight: bold;
    left: -3px;
    line-height: 16px;
    min-width: 10px;
    padding: 1px 4px;
    position: absolute;
    z-index: 10000;
    text-align: center;
    top: -2px;
    background-image: -webkit-gradient(radial, 0% 0%, 0, 0% 0%, 100, color-stop(0%, #fc0d1b), color-stop(100%, #820e0b));
    background-image: -webkit-radial-gradient(top left, #fc0d1b, #820e0b);
    background-image: -moz-radial-gradient(top left, #fc0d1b, #820e0b);
    background-image: -o-radial-gradient(top left, #fc0d1b, #820e0b);
    background-image: radial-gradient(top left, #fc0d1b, #820e0b);
    -webkit-border-radius: 50px;
    -moz-border-radius: 50px;
    -ms-border-radius: 50px;
    -o-border-radius: 50px;
    border-radius: 50px;
    -webkit-box-shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
    -moz-box-shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.4);
    font-size: 12px;
    text-shadow: none;
}

JavaScript

function change() {
    $('#mainmenu3').prop('data-badge','444');
}