memo) React - state
<!DOCTYPE html>
<html lang="en">
<body>
<div id="root"></div>
</body>
<script src="https://unpkg.com/react@17.0.2/umd/react.production.min.js"></script>
<script src="https://unpkg.com/react-dom@17.0.2/umd/react-dom.production.min.js"></script>
<script src="https://unpkg.com/@babel/standalone/babel.min.js"></script>
<script type="text/babel">
function MinutesToHours() {
const [amount, setAmount] = React.useState(0); // default 값: 0
const [inverted, setInverted] = React.useState(false);
const onChange = (event) => {
setAmount(event.target.value);
};
const reset = () => setAmount(0);
const onFlip = () => {
reset();
setInverted((current) => !current);
};
return (
<div>
<div>
<label htmlFor="minutes">Minutes</label>
<input
value={inverted ? amount * 60 : amount}
id="minutes"
placeholder="Minutes"
type="number"
onChange = {onChange}
disabled={inverted}
/>
</div>
<div>
<label htmlFor="hours">Hours</label>
<input
value={inverted ? amount : Math.round(amount / 60)}
id="hours"
placeholder="Hours"
type="number"
disabled={!inverted}
onChange={onChange}
/>
</div>
<button onClick={reset}>Reset</button>
<button onClick={onFlip}>{inverted ? "Turn back" : "Invert"}</button>
</div>
);
}
function KmToMiles() {
return <h3>KM 2 M</h3>;
}
function App() {
const [index, setIndex] = React.useState();
const onSelect = (event) => {
setIndex(event.target.value);
}
return (
<div>
<h1>Super Converter</h1>
<select value={index} onChange={onSelect}>
<option value="xx">Select your unit</option>
<option value="0">Minutes & Hours</option>
<option value="1">Km & Miles </option>
</select>
{index === "xx" ? "Please select your unit" : null}
{index === "0" ? <MinutesToHours /> : null}
{index === "1" ? <KmToMiles /> : null}
</div>
);
}
const root = document.getElementById("root");
ReactDOM.render(<App />, root); // App 컴포넌트는 안에 다른 2개의 컴포넌트를 렌더링하고 있음! -> min, km
</script>
</html>
console.log("불꽃남자 정대만"); 🏀❤