JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/3.2.1/css/font-awesome.min.css">
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap.min.css">
<form role="form">
  <div class="form-group">
    <input type="text" class="form-control empty" id="iconified" placeholder="&#xF002;"/>
  </div>
</form>

CSS

input.empty {
    font-family: FontAwesome;
    font-style: normal;
    font-weight: normal;
    text-decoration: inherit;
}

JavaScript

$('#iconified').on('keyup', function() {
    var input = $(this);
    if(input.val().length === 0) {
        input.addClass('empty');
    } else {
        input.removeClass('empty');
    }
});