我正在试图弄清楚为什么我的useEffect钩子不断被多次调用,即使依赖项具有相同的值。我使用以下代码:
import React, { useEffect, useState } from 'react'
import PropTypes from 'prop-types'
import Cards from '../../../cards/Cards'
import UserCard from '../../../cards/users/Card'
import LoadingContainer from '../.
我在读反应钩子的概念。我通过了一条规则,上面写着Don't call React hooks inside conditions。在这里,他们提供了解释。
function Form() {
// 1. Use the name state variable
const [name, setName] = useState('Mary');
// 2. Use an effect for persisting the form
useEffect(function persistForm() {
localStorage.setItem(
假设我有下面的代码,它有一个useState钩子,它的默认值是一个空数组:
import React, { useState, useEffect } from "react";
export default () => {
const [fooData, setFooData] = useState([]);
useEffect(() => {
// some data fetching from and API happens here... example: setFooData(data);
// this is what I
当变量‘UseState’发生变化时如何更新matchUrl()。当导航到另一条路由时,“matchUrl”值会发生变化。这些更改反映在console.log和'h1‘标签上。但是,它保留了旧的价值,而不是usestate()。
import React, {useState} from 'react'
import useInfinityScroll from './hooks/useInfinityScroll'
import names form './data/names'
function TableList({ ma
我正在尝试将字符串数组keys呈现为一个React组件。keys是用户按下的键(但我只是为了这个示例对它们进行了硬编码)。
import { useState } from "react";
import * as ReactDOM from "react-dom";
let keys = ["a", "b"];
function App() {
let [keysState, setKeysState] = useState([]);
setKeysState((keysState = keys));
ret