您好,我有一个列表组件,它呈现了一些<Card>
具有的组件prop
isSelected
。因为很多事情发生在一个<Card>
组件都有isSelected === true
我加了state
上<List>
组件,我要当有人点击一个卡检查:
1)如果没有以前选择的项目(state===null
将其ID添加到状态)
2)如果某人在状态中已经选择了某个项目的情况下单击同一项目或另一项目,则仅取消选择活动项目。
import {Card} from "./Card";
import cloneDeep from 'lodash/cloneDeep';
const List = () => {
const [selectedCard, setSelectedCard] = useState(null);
const onCardClick = id => {
console.debug(selectedCard, id)
const newSelectedCard = cloneDeep(selectedCard);
// if he clicks another item while an item is active
// or if he clicks the same item while active
// should just make it inactive
if (newSelectedCard !== null || newSelectedCard === id) {
setSelectedCard(null)
} else {
setSelectedCard(id)
}
console.debug(selectedCard, id)
}
return (
<ul className="card-list">
{cardData.map(card => (
<Card
onClick={() => onCardClick(card.id)}
key={card.id}
isSelected={selectedCard === card.id}
{...card}
/>
))}
</ul>
)
}
export const CardList = () => (
<List/>
);
问题是2console.debugs
显示相同的值,这意味着状态不会立即更新,并且Im在这里和那里遇到一些奇怪的行为。我在这里想念什么吗?
基本上你需要遵循以下三个条件
if(newSelectedCard === null){
setSelectedCard(id)
}
else if(newSelectedCard === id){
setSelectedCard(null);
}
else{
setSelectedCard(id)
}
这是完整的示例:
import cloneDeep from 'lodash/cloneDeep';
import React, {useState} from "react";
const List = () => {
const [cardData, setCardData] = useState([
{id: 1, title: 'First Card'},
{id: 2, title: 'Second Card'},
{id: 3, title: 'Third Card'},
{id: 4, title: 'Fourth Card'},
]);
const [selectedCard, setSelectedCard] = useState(null);
const onCardClick = id => {
console.log(selectedCard, id);
const newSelectedCard = cloneDeep(selectedCard);
// if he clicks another item while an item is active
// or if he clicks the same item while active
// should just make it inactive
if(newSelectedCard === null){
setSelectedCard(id)
}
else if(newSelectedCard === id){
setSelectedCard(null);
}
else{
setSelectedCard(id)
}
console.log(selectedCard, id)
};
return (
<ul className="card-list">
{cardData.map(card => (
<Card
onClick={() => onCardClick(card.id)}
key={card.id}
isSelected={selectedCard === card.id}
{...card}
/>
))}
</ul>
)
};
export const CardList = () => (
<List/>
);
const Card = (props) => {
const backColor = props.isSelected? '#F9740E' : '#3FB566';
return (
<div onClick={() => props.onClick()}>
<div style={{backgroundColor: backColor, border: '1px solid darkgreen', color: 'white', padding: 10, marginBottom: 10}}>
<h3>{props.id}</h3>
<h4>{props.title}</h4>
</div>
</div>
);
};
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