基于Taro实现小程序custom-tab-bar

环境:

• taro -v 3.6.6
• react -v 18.0.0

配置app.config.js

找到根目录下的app.config.js配置tarbar

tabBar: {
  custom: true,
  color: '#000000',
  selectedColor: '#DC143C',
  backgroundColor: '#ffffff',
  list: [
    {
      pagePath: "pages/home/index",
      text: "home",
    }
    {
      pagePath: "pages/mine/index",
      text: "mine",
    }
  ]
}

页面配置

在使用tab-bar的页面添加 usingComponents: {}

创建custom-tab-bar组件

warn: 必须在src下,目录名必须为custom-tab-bar

• 新建 custom-tab-bar/index.jsx文件

import { useState, useEffect } from "react";
import { switchTab, getCurrentPages } from "@tarojs/taro";
import { CoverView, CoverImage } from "@tarojs/components";

import tabbar_home_on from "../images/tabbar_home_on.png";
import tabbar_home from "../images/tabbar_home.png";
import tabbar_mine_on from "../images/tabbar_mine_on.png";
import tabbar_mine from "../images/tabbar_mine.png";

import "./index.scss";

const tabbarConfig = {
  color: "#000000",
  selectedColor: "#DC143C",
  list: [
    {
      pagePath: "/pages/home/index",
      selectedIconPath: tabbar_home_on,
      iconPath: tabbar_home,
      text: "",
    },
    {
      pagePath: "/pages/mine/index",
      selectedIconPath: tabbar_mine_on,
      iconPath: tabbar_mine,
      text: "",
    },
  ],
};

function CustomTabBar() {
  const { list, color, selectedColor } = tabbarConfig;
  const pages = getCurrentPages();
  const currentPage = pages[0];
  const [selected, setselected] = useState(0);

  useEffect(() => {
    const index = list.findIndex(
      (item) => item.pagePath === "/" + currentPage.route
    );
    if (index > -1) {
      setselected(index);
    }
  }, [currentPage.route]);

  const handleSwitchTab = (url) => {
    switchTab({ url });
  };

  return (
    <CoverView className='tab-bar'>
      <CoverView className='tab-bar-border'></CoverView>
      {list.map((item, index) => {
        return (
          <CoverView
            key={index}
            className='tab-bar-item'
            onClick={() => handleSwitchTab(item.pagePath)}
          >
            <CoverImage
              src={selected === index ? item.selectedIconPath : item.iconPath}
            />
            <CoverView
              style={{ color: selected === index ? selectedColor : color }}
            >
              {item.text}
            </CoverView>
          </CoverView>
        );
      })}
    </CoverView>
  );
}

export default CustomTabBar;

• 新建 custom-tab-bar/index.scss文件

.tab-bar {
  position: fixed;
  bottom: env(safe-area-inset-bottom);
  left: 50%;
  width: 80%;
  transform: translateX(-50%);
  height: 100px;
  border-radius: 50px;
  background: rgba(255, 192, 203, .7);
  display: flex;
}

.tab-bar-border {
  background-color: rgba(0, 0, 0, 0.33);
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 1px;
  transform: scaleY(0.5);
}

.tab-bar-item {
  flex: 1;
  text-align: center;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}

.tab-bar-item cover-image {
  width: 54px;
  height: 54px;
}

.tab-bar-item cover-view {
  font-size: 20px;
}

• 新建 custom-tab-bar/index.config.js文件

export default {
  "component": true
}

遇到的坑

• 切换tab时，custom-tab-bar组件重加载问题

问题描述:
在点击切换tab时，我们期望custom-tab-bar组件不进行重新渲染，因为重新渲染会导致selected值错误的进行初始化，从而导致页面渲染异常
解决办法:

1. 使用reducer等在外部储存selected状态,避免selected值丢失,但由于这种方法引入的一个包,增加了项目体积，所以我选择下面的方式
2. 通过监听路由的变化来改变selected值，如下

 useEffect(() => {
  const index = list.findIndex(
    (item) => item.pagePath === "/" + currentPage.route
  );
  if (index > -1) {
    setselected(index);
  }
}, [currentPage.route]);