[英]How can I display the results of a function in React?
我想在輸入后在段落標簽中顯示 function 的結果。 這是我嘗試過的:
import React, { useState } from "react";
const Measurement = () => {
const [brightness, setBrightness] = useState(0);
const [darkness, setDarkness] = useState(0);
const checkLumens = () => {
if (brightness > 120) {
return "High";
}
if (darkness < 80) {
return "Low";
}
else {
return "Not Set";
}
};
return (
<div>
<input
type="number"
onChange={(event) => setBrightness(event.target.value)}
/>
<button>Show</button>
<p>{checkLumens()}</p> //Hide by default and show {checkLumens()} after button click
</div>
);
};
export default Measurement;
謝謝您的幫助!
只需添加一個新的 state 變量:
import React, { useState } from "react";
const Measurement = () => {
const [brightness, setBrightness] = useState(0);
const [darkness, setDarkness] = useState(0);
const [showLumens, setShowLumens] = useState(false);
const checkLumens = () => {
if (brightness > 120) {
return "High";
}
if (darkness < 80) {
return "Low";
}
else {
return "Not Set";
}
};
return (
<div>
<input
type="number"
onChange={(event) => setBrightness(event.target.value)}
/>
<button onClick={() => setShowLumens(true)}>Show</button>
<p>{showLumens ? checkLumens() : null}</p> //Hide by default and show {checkLumens()} after button click
</div>
);
};
export default Measurement;
import React, { useState, useEffect } from "react"; const Measurement = () => { const [brightness, setBrightness] = useState(0); const [darkness, setDarkness] = useState(0); const [lumens, setLumens] = useState('Not Set') const [show, setShow] = useState(false) useEffect(() => { if (brightness > 120) { setLumens("High"); } if (darkness < 80) { setLumens("Low"); } else { setLumens("Not Set"); } }, [darkness, brightness]) return ( <div> <input type="number" onChange={(event) => setBrightness(event.target.value)} /> <button onClick={() => setShow(true)}>Show</button> <p>{show && lumens}</p> //Hide by default and show {checkLumens()} after button click </div> ); }; export default Measurement;
創建一個 state 以使用 useState 顯示和隱藏流明值,並在單擊按鈕時更改值
const Measurement = () => {
const [brightness, setBrightness] = useState(0);
const [darkness, setDarkness] = useState(0);
const [showLumens, setShowLumnes] = useState(false);
const checkLumens = () => {
if (brightness > 120) {
return "High";
}
if (darkness < 80) {
return "Low";
}
else {
return "Not Set";
}
};
return (
<div>
<input
type="number"
onChange={(event) => setBrightness(event.target.value)}
/>
<button onClick={()=>setShowLumnes(true)}>Show</button>
{showLumens && <p>{checkLumens()}</p>}
</div>
);
};
export default Measurement;
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