export const Main = () => {
    const [title, setTitle] = useState('');
    
    return (
        <ChildComponent
            title={title}
            onChange={e => setTitle(e.target.value)}
        />
    );
};

export const ChildComponent = ({ title, onChange }) => {
    return (
        <Box component="form" onSubmit={() => {}} noValidate mt={5}>
            <TextField
                fullWidth
                id="title"
                label="Title"
                name="title"
                autoComplete="title"
                autoFocus
                color="primary"
                variant="filled"
                InputLabelProps={{ shrink: true }}
                value={title}
                onChange={onChange}
            />
        </Box>
    );
};

// `date` is a `Date` object
const formatYmd = date => date.toISOString().slice(0, 10);

// Example
formatYmd(new Date());      // 2020-05-06

// Vanilla JS Solution:
var app = document.getElementById('app');

var typewriter = new Typewriter(app, { loop: true });

typewriter
    .typeString("I'm John and I'm a super cool web developer")
    .pauseFor(3000)
    .deleteChars(13) // "web developer" = 13 characters
    .typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!"
    .start();

// React Solution:
import Typewriter from 'typewriter-effect';

<Typewriter
    options={{ loop: true }}
    onInit={typewriter => {
        typewriter
            .typeString("I'm John and I'm a super cool web developer")
            .pauseFor(3000)
            .deleteChars(13) // "web developer" = 13 characters
            .typeString("person to talk with!") // Will display "I'm John and I'm a super cool person to talk with!"
            .start();
    }}
/>

const head = arr => (arr && arr.length ? arr[0] : undefined);

head([1, 2, 3]); // 1
head([]); // undefined
head(null); // undefined
head(undefined); // undefined

//JavaScript program to swap two variables

//take input from the users
let a = prompt('Enter the first variable: ');
let b = prompt('Enter the second variable: ');

//using destructuring assignment
[a, b] = [b, a];

console.log(`The value of a after swapping: ${a}`);
console.log(`The value of b after swapping: ${b}`);

function Clock(props) {
  return (
    <div>
      <h1>Hello, world!</h1>
      <h2>It is {props.date.toLocaleTimeString()}.</h2>
    </div>
  );
}

function tick() {
  ReactDOM.render(
    <Clock date={new Date()} />,
    document.getElementById('root')
  );
}

setInterval(tick, 1000);