JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <label for="Area">Full Area:</label>
    <input type="text" value="" name="FullArea" id="FullArea" class="numeric">
</div><div>
    <label for="Area">Full Area:</label>
    <input type="text" value="" name="FullArea" id="FullArea" class="numeric">
</div><div>
    <label for="Area">Full Area:</label>
    <input type="text" value="" name="FullArea" id="FullArea" class="numeric">
</div><div>
    <label for="Area">Full Area:</label>
    <input type="text" value="" name="FullArea" id="FullArea" class="numeric">
</div>

JavaScript

var em = $("<em>type only numeric formatted text<em>").hide();
$('.numeric').keypress(function (e) {
    var key_code = e.which;
    if (key_code != 8 && key_code != 0 && (key_code < 48 || key_code > 57)) {
       $(this).next("em").show();
       return false ;
    }
    else {
       $(this).next("em").hide();
    }
}).after(em);