JSFiddle - React, Tailwind, and code Playground

by Walter Rumsby

HTML

<input id="calc" type="text"/>
<br />
<div id='result' />

JavaScript

/*global $ */
(function() {
    'use strict';

    $('#calc').on('blur', function(e) {
        var val = $('#calc').val(),
            result;

        if (/[^\d\s+\-*\/]+/g.test(val)) {
            result = 'undefined';
        } else {
            result = eval(val);
        }

        $('#calc').val(result);
    });
}());