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React -3 State 본문

🖥️Frontend/React

React -3 State

비엔 Vien 2025. 3. 11. 12:34
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
</head>
<body>
<div id="root"></div>
</body>
<script type="text/babel">
function MinutesToHours() {
const [amount, setAmount] = React.useState(0);
const [flipped, setFlipped] = React.useState(false);
const onChange = (event) => {
setAmount(event.target.value);
};
const reset = () => setAmount(0);
const onFlip = () => setFlipped((current) => !current);
return (
<div>
<div>
<label htmlFor="minutes">Minutes</label>
<input
value={flipped ? amount * 60 : amount}
id="minutes"
placeholder="Minutes"
type="number"
onChange={onChange}
// disabled={flipped === true}
disabled={flipped}
/>
</div>
<div>
<label htmlFor="hours">Hours</label>
<input
value={flipped ? amount : Math.round(amount / 60)}
id="hours"
placeholder="Hours"
type="number"
// disabled={flipped === false}
disabled={!flipped}
onChange={onChange}
/>
</div>
<button onClick={reset}>Reset</button>
<button onClick={onFlip}>Flip</button>
</div>
);
}

function KmToMiles() {
const [amount, setAmount] = React.useState(0);
const [flipped, setFlipped] = React.useState(false);
const onChange = (event) => {
setAmount(event.target.value);
};
const reset = () => setAmount(0);
const onFlip = () => setFlipped((current) => !current);
return (
<div>
<div>
<label htmlFor="km">Kilometers</label>
<input
value={flipped ? amount / 0.621371 : amount}
id="km"
placeholder="Kilometers"
type="number"
onChange={onChange}
disabled={flipped}
/>
</div>
<div>
<label htmlFor="miles">Miles</label>
<input
value={flipped ? amount : amount * 0.621371}
id="miles"
placeholder="Miles"
type="number"
disabled={!flipped}
onChange={onChange}
/>
</div>
<button onClick={reset}>Reset</button>
<button onClick={onFlip}>Flip</button>
</div>
);
}

function App() {
const [index, setIndex] = React.useState("xx");
const onSelect = (event) => {
setIndex(event.target.value); //index 값을 업데이트(event.target.value는 사용자가 선택한 <option>의 값)
};
return (
<div>
<h1>Super Converter</h1>
<select value={index} onChange={onSelect}>
<option value="xx">Select your units</option>
<option value="0">Minutes & Hours </option>
<option value="1">Km & Miles </option>
</select>
<hr/>
{index === "xx" ? "Please select your units" : null}
{index === "0" ? <MinutesToHours /> : null}
{index === "1" ? <KmToMiles /> : null}
</div>
);
}
const root = document.getElementById("root");

ReactDOM.render(<App />, root);
</script>
</html>

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