JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet"  href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.7.0/themes/smoothness/jquery-ui.css" media="screen" /><button type="submit"><span class="ui-icon ui-icon-mail-closed"></span>Send</button>

CSS

button span.ui-icon {
    display: inline;
    float: left;
    margin-right: 2px;
}
button{width:75px;}

JavaScript

$('#content button').each(function() {                
    var icon = $(this).find('span.ui-icon');
    var primaryIcon = icon.attr('class').replace(/ui-icon\s?/, '');
    icon.remove();
    $(this).button({ icons: {primary: primaryIcon }, label: $(this).text() });
});