做背景图获取网站嵌入式培训

为什么要使用自定义 Hooks

自定义 Hooks 是 React 中一种复用逻辑的机制，通过它们可以抽离组件中的逻辑，使代码更加简洁、易读、易维护。它们可以在多个组件中复用相同的逻辑，减少重复代码。

1、useThrottle

代码

import React,{ useRef, useState,useEffect } from "react";/*** useThrottle：一个节流的 hook，用于限制状态更新的频率。** @param {any} initialState 初始状态* @param {number} delay 节流间隔时间，默认为 500 毫秒* @returns {any} 节流后的状态*/
export const useThrottle = (initialState, delay = 5000) => {const [state, setState] = useState(initialState);const timeout = useRef();const nextValue = useRef(null);const hasNextValue = useRef(false);useEffect(() => {if (timeout.current) {nextValue.current = initialState;hasNextValue.current = true;} else {setState(initialState);const timeoutCallback = () => {if (hasNextValue.current) {setState(nextValue.current);hasNextValue.current = false;}timeout.current = undefined;};timeout.current = setTimeout(timeoutCallback, delay);}return () => {timeout.current && clearTimeout(timeout.current);}}, [initialState]);return state;
};

用法

import { useThrottle } from './useThrottle';const value = useThrottle(state, 500);

2、useVirtual

代码

import { useEffect, useState } from 'react';/*** useVirtual：一个虚拟滚动的 hook，用于优化长列表的渲染性能。** @param {object} listRef 列表的引用对象* @param {Array} list 初始列表数据* @param {boolean} isFullScreen 是否全屏显示* @returns {Array} 显示在视图中的列表数据和 padding 样式*/
export const useVirtual = (listRef, list, isFullScreen) => {const origin = list;let viewHeight = null;let itemHeight = 0;let dur = 0;const rootFontSize = parseInt(document.documentElement.style.fontSize);const [viewList, setViewList] = useState(list);const [startIndex, setStartIndex] = useState(0);const [endIndex, setEndIndex] = useState(0);const [padding, setPadding] = useState({paddingTop: 0,paddingBottom: 0,});useEffect(() => {init(listRef);}, []);useEffect(() => {initData(listRef.current);update();}, [startIndex]);function init(ref) {initData(ref.current);render(startIndex, dur + 1);eventBind(ref.current);}function initData(dom) {const target = isFullScreen ? document.documentElement : dom;viewHeight = isFullScreen ? target.offsetHeight : target.parentNode.offsetHeight;itemHeight = target.getElementsByClassName('virtual-item')[0].offsetHeight;dur = Math.floor(viewHeight / itemHeight);}function eventBind(dom) {const eventTarget = isFullScreen ? window : dom.parentNode;eventTarget.addEventListener('scroll', handleScroll, false);}function render(startIndex, endIndex) {setViewList(() => origin.slice(startIndex, endIndex));setEndIndex(() => startIndex + dur + 1);}function handleScroll(e) {e.stopPropagation();const target = isFullScreen ? document.documentElement : listRef.current.parentNode;setStartIndex(() => Math.floor(target.scrollTop / itemHeight));}function update() {if (startIndex === endIndex) return;setEndIndex(() => startIndex + dur);render(startIndex, endIndex);setPadding(() => {return {paddingTop: (startIndex * itemHeight) / rootFontSize,paddingBottom: ((origin.length - endIndex) * itemHeight) / rootFontSize,};});}return [viewList, padding];
};

用法

import { useRef } from 'react';
import { useVirtual } from './useVirtual';const listRef = useRef();
const [viewList, padding] = useVirtual(listRef, initialList, false);

3、useCopyToClipboard

代码

import { message } from 'antd';/*** useCopyToClipboard：一个 hook，用于复制文本到剪贴板。** @returns {Array} 包含单个函数 `handleCopy`，用于复制文本到剪贴板*/
const useCopyToClipboard = () => {function handleCopy(text) {if (text) {let input = document.createElement('input');input.type = 'text';input.value = text;input.style.position = 'fixed';input.style.opacity = '0';document.body.appendChild(input);input.select();if (document.execCommand('copy')) {message.success('复制成功');} else {message.error('复制失败');}document.body.removeChild(input);} else {message.error('复制失败');}}return [handleCopy];
};export default useCopyToClipboard;

用法

import useCopyToClipboard from './useCopyToClipboard';const [handleCopy] = useCopyToClipboard();const copyText = () => {handleCopy('需要复制的文本');
};

4、useSmoothEnter

代码

import { useState, useEffect, useRef } from 'react';/*** useSmoothEnter：一个 hook，在 DOM 元素进入视口时添加平滑的进入动画。** @returns {object} ref - 一个可以附加到 DOM 元素的 ref 对象，用于动画效果*/
const useSmoothEnter = () => {const ref = useRef(null);const [isVisible, setIsVisible] = useState(false);const [animationStyle, setAnimationStyle] = useState({animation: '',animationPlayState: 'paused',});useEffect(() => {const observer = new IntersectionObserver((entries) => {const [entry] = entries;setIsVisible(entry.isIntersecting);});const element = ref.current;if (element) {observer.observe(element);return () => {observer.unobserve(element);};}}, [ref]);useEffect(() => {if (isVisible) {setAnimationStyle({animation: 'enterAnimation 1s ease',animationPlayState: 'running',});}}, [isVisible]);useEffect(() => {const element = ref.current;if (element) {element.style.animation = animationStyle.animation;element.style.animationPlayState = animationStyle.animationPlayState;}}, [animationStyle]);return ref;
};export default useSmoothEnter;

用法

import useSmoothEnter from './useSmoothEnter';const ref = useSmoothEnter();return <div ref={ref} className="animated-element">内容</div>;