function App() {
const [ text, setText ] = React.useState('');
const append = e => setText(text + e.target.textContent);
const clear = () => setText('');
return (<>
<div className="row">
<textarea value={text} readOnly />
</div>
<div className="row">
{Array.from({ length: 10 }, (_, i) => (
<button onClick={append}>{i}</button>
))}
</div>
<div className="row">
<button onClick={clear}>clear</button>
</div>
</>);
}
.row {
display: flex;
justify-content: center;
padding: 5px;
gap: 5px;
}