<script src="https://unpkg.com/react@17.0.2/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@17.0.2/umd/react-dom.development.js"></script>
<script src="https://unpkg.com/@babel/standalone@7.14.7/babel.min.js"></script>
<script type="text/babel">
const { useState } = React;
const str = "hello, world!"; // Replace with your string
const isFirstLetterUppercase = str => {
const firstCharCode = str.charCodeAt(0);
return firstCharCode >= 65 && firstCharCode <= 90;
const capitalizeFirstLetter = str => {
if (isFirstLetterUppercase(str)) {
const firstCharCode = str.charCodeAt(0);
const capitalizedFirstLetter = String.fromCharCode(firstCharCode - 32);
return capitalizedFirstLetter + str.slice(1);
const modifiedString = capitalizeFirstLetter(str);
<div className='container'>
<h3 className='title'> use charCodeAt() Method</h3>
<p className='string-info'>String: {str}</p>
<p className='uppercase-check'>Is the first letter uppercase? {isFirstLetterUppercase(str).toString()}</p>
<p className='modified-string'>Modified String: {modifiedString}</p>
ReactDOM.render(<App />, document.getElementById("app"));
font-family: Arial, sans-serif;
box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.2);