JSFiddle - React, Tailwind, and code Playground

HTML

<div class="input">
    <input name="name" placeholder="name" />
    <span class="remaining"></span>
</div>

CSS

input {
    border: none;
}
.input {
    border: 1px solid #ccc;
    float: left;
}

JavaScript

function characterLimit() {
    var remaining = 120 - $('input').val().length;
    $('.remaining').text(remaining);
}
characterLimit();

$('input').keyup(function() {
    characterLimit();
});