Kuunganisha Viingilio kwa Safu katika React

Acha katika hali notes ihifadhi safu:

function App() {
	const [notes, setNotes] = useState([1, 2, 3]);
	
	return <div>
		
	</div>;
}

Acha tuwe pia na kitendo saidizi, kinachopata jumla ya vipengele vya safu:

function getSum(arr) {
	let sum = 0;
	
	for (const elem of arr) {
		sum += +elem;
	}
	
	return sum;
}

function App() {
	...
}

Wacha tupate na tuonyeshe jumla ya vipengele vya safu yetu kutoka kwenye hali, tukitumia kitendo chetu saidizi:

function App() {
	const [notes, setNotes] = useState([1, 2, 3]);
	
	return <div>
		{getSum(notes)}
	</div>;
}

Wacha sasa tutengeneze viingilio vitatu na kwenye value kila kikiingiza andika kipengele kimoja cha safu:

function App() {
	const [notes, setNotes] = useState([1, 2, 3]);
	
	return <div>
		<input value={notes[0]} />
		<input value={notes[1]} />
		<input value={notes[2]} />
		
		{getSum(notes)}
	</div>;
}

Wacha sasa tuongeze tukio onChange kwenye viingilio vyetu. Wakati huu tutafanya kitendo kimoja cha pamoja kinachoshughulikia tukio hili:

function App() {
	const [notes, setNotes] = useState([1, 2, 3]);
	
	function changeHandler(index, event) {
		// kitendo cha pamoja kinachoshughulikia
	}
	
	return <div>
		<input value={notes[0]} onChange={event => changeHandler(0, event)} />
		<input value={notes[1]} onChange={event => changeHandler(1, event)} />
		<input value={notes[2]} onChange={event => changeHandler(2, event)} />
		
		{getSum(notes)}
	</div>;
}

Kama unavyoona, kitendo changeHandler hupokea nambari ya kwanza ya kipengele cha safu, ambacho kikiingiza kinaharakisha.

Kwa nambari hii tunaweza kubadilisha kipengele cha safu kwa yaliyomo kwenye kikiingiza.

Wacha tutengeneze hii:

function changeHandler(index, event) {
	setNotes([...notes.slice(0, index), event.target.value, ...notes.slice(index + 1)]);
}

Sasa itawezekana kuhariri kikiingiza chochote, wakati huu safu itabadilika kwa nguvu na, ipasavyo, jumla ya vipengele vyake itakokotolewa upya.

Wacha tukusanye msimbo wetu wote pamoja:

function App() {
	const [notes, setNotes] = useState([1, 2, 3]);
	
	function changeHandler(index, event) {
		setNotes([...notes.slice(0, index), event.target.value, ...notes.slice(index + 1)]);
	}
	
	return <div>
		<input value={notes[0]} onChange={event => changeHandler(0, event)} />
		<input value={notes[1]} onChange={event => changeHandler(1, event)} />
		<input value={notes[2]} onChange={event => changeHandler(2, event)} />
		
		{getSum(notes)}
	</div>;
}

Inawezekana kufanya hivi, ili viingilio vitengenezwe kwenye kitanzi:

function App() {
	const [notes, setNotes] = useState([1, 2, 3]);
	
	function changeHandler(index, event) {
		setNotes([...notes.slice(0, index), event.target.value, ...notes.slice(index + 1)]);
	}
	
	const result = notes.map((note, index) => {
		return <input
			key={index}
			value={note}
			onChange={event => changeHandler(index, event)}
		/>;
	});
	
	return <div>
		{result}
		{getSum(notes)}
	</div>;
}

Imetolewa safu ifuatayo:

[1, 2, 3, 4, 5, 6, 7, 8, 9]

Onyesha kwenye skrini wastani wa kihisabati vipengele vya safu hii. Kwenye kitanzi tengeneza viingilio vya kuhariri vipengele.