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
我一直试图理解react的useState钩子的工作原理,但是我无法理解它是如何实现的,比如在这个JavaScript代码中。
import React, { useState } from 'react';
function Example() {
// Declare a new state variable, which we'll call "count"
const [count, setCount] = useState(0);
function onClick()
{setCount(2)
}
return (
每次单击increment按钮时:
期望:当前count已记录
实际:count的初始值,即记录为3
import React, { useState, useEffect } from "react";
function SomeLibrary(props) {
const [mapState, setMapState] = useState(undefined);
useEffect(() => {
console.log("setting map");
// Run exactly once at mount of com