import React, { useState, useEffect } from "react"; import { Typography, Paper } from "@mui/material"; interface IProps { onFinish: () => void; } export function Countdown(props: IProps): React.ReactElement { const [x, setX] = useState(3); useEffect(() => { if (x === 0) { props.onFinish(); return; } setTimeout(() => setX(x - 1), 300); }); return ( Get Ready! {x} ); }