vue2、vue3实现暗黑模式
1、序言
elementPlus、naive UI这些UI组件里面封装好了暗黑模式，直接使用相关api即可实现暗黑模式切换功能，而elementUI没有封装好，我们可以看看elementPlus、naive UI如何实现暗黑模式，然后在elementUI中模仿，从而实现暗黑模式！
2、vue3实现暗黑模式
2.1、使用
（1）npm i @vueuse/core， 这个里面封装了很多hook工具函数： VueUse | VueUse
（2）import { useDark, useToggle } from '@vueuse/core'
（3）在<script> 下使用：
<script setup> import { useDark, useToggle} from '@vueuse/core'const isDark = useDark(); </script> <style scoped>（4）useDark()可以获取当前的主题模式是不是暗黑模式，返回的是布尔值，useToggle()类似于开关，能将useDark()取反，实现主题模式切换效果
（5）main.js中引入暗黑模式的样式包：
import 'element-plus/dist/index.css' ：引入elementplus推荐的light模式的样式文件
import 'element-plus/theme-chalk/dark/css-vars.css'：是elementplus实现的dark模式的样式文件
2.2、原理
结论：暗黑模式时 import 'element-plus/theme-chalk/dark/css-vars.css' 覆盖 light模式中
import 'element-plus/dist/index.css' 的样式文件
（1）会给html添加个class = "dark" 选择器
暗黑模式：
light模式
（2）dark模式会在 'element-plus/theme-chalk/dark/css-vars.css' 进行样式覆盖
'element-plus/theme-chalk/dark/css-vars.css'
html.dark {color-scheme: dark;--el-color-primary: #409eff;--el-color-primary-light-3: #3375b9;--el-color-primary-light-5: #2a598a;--el-color-primary-light-7: #213d5b;--el-color-primary-light-8: #1d3043;--el-color-primary-light-9: #18222c;--el-color-primary-dark-2: #66b1ff;--el-color-success: #67c23a;--el-color-success-light-3: #4e8e2f;--el-color-success-light-5: #3e6b27;--el-color-success-light-7: #2d481f;--el-color-success-light-8: #25371c;--el-color-success-light-9: #1c2518;--el-color-success-dark-2: #85ce61;--el-color-warning: #e6a23c;--el-color-warning-light-3: #a77730;--el-color-warning-light-5: #7d5b28;--el-color-warning-light-7: #533f20;--el-color-warning-light-8: #3e301c;--el-color-warning-light-9: #292218;--el-color-warning-dark-2: #ebb563;--el-color-danger: #f56c6c;--el-color-danger-light-3: #b25252;--el-color-danger-light-5: #854040;--el-color-danger-light-7: #582e2e;--el-color-danger-light-8: #412626;--el-color-danger-light-9: #2b1d1d;--el-color-danger-dark-2: #f78989;--el-color-error: #f56c6c;--el-color-error-light-3: #b25252;--el-color-error-light-5: #854040;--el-color-error-light-7: #582e2e;--el-color-error-light-8: #412626;--el-color-error-light-9: #2b1d1d;--el-color-error-dark-2: #f78989;--el-color-info: #909399;--el-color-info-light-3: #6b6d71;--el-color-info-light-5: #525457;--el-color-info-light-7: #393a3c;--el-color-info-light-8: #2d2d2f;--el-color-info-light-9: #202121;--el-color-info-dark-2: #a6a9ad;--el-box-shadow: 0px 12px 32px 4px rgba(0, 0, 0, 0.36), 0px 8px 20px rgba(0, 0, 0, 0.72);--el-box-shadow-light: 0px 0px 12px rgba(0, 0, 0, 0.72);--el-box-shadow-lighter: 0px 0px 6px rgba(0, 0, 0, 0.72);--el-box-shadow-dark: 0px 16px 48px 16px rgba(0, 0, 0, 0.72), 0px 12px 32px #000000, 0px 8px 16px -8px #000000;--el-bg-color-page: #0a0a0a;--el-bg-color: #141414;--el-bg-color-overlay: #1d1e1f;--el-text-color-primary: #E5EAF3;--el-text-color-regular: #CFD3DC;--el-text-color-secondary: #A3A6AD;--el-text-color-placeholder: #8D9095;--el-text-color-disabled: #6C6E72;--el-border-color-darker: #636466;--el-border-color-dark: #58585B;--el-border-color: #4C4D4F;--el-border-color-light: #414243;--el-border-color-lighter: #363637;--el-border-color-extra-light: #2B2B2C;--el-fill-color-darker: #424243;--el-fill-color-dark: #39393A;--el-fill-color: #303030;--el-fill-color-light: #262727;--el-fill-color-lighter: #1D1D1D;--el-fill-color-extra-light: #191919;--el-fill-color-blank: transparent;--el-mask-color: rgba(0, 0, 0, 0.8);--el-mask-color-extra-light: rgba(0, 0, 0, 0.3)
}html.dark .el-button {--el-button-disabled-text-color: rgba(255, 255, 255, 0.5)
}html.dark .el-card {--el-card-bg-color: var(--el-bg-color-overlay)
}html.dark .el-empty {--el-empty-fill-color-0: var(--el-color-black);--el-empty-fill-color-1: #4b4b52;--el-empty-fill-color-2: #36383d;--el-empty-fill-color-3: #1e1e20;--el-empty-fill-color-4: #262629;--el-empty-fill-color-5: #202124;--el-empty-fill-color-6: #212224;--el-empty-fill-color-7: #1b1c1f;--el-empty-fill-color-8: #1c1d1f;--el-empty-fill-color-9: #18181a
}（3）css文件中，--开头的为自定义变量，要使用它时var(--自定义变量)，从而实现变量复用，减少冗余的css样式
（4）举个例子：el-card
element-plus/dist/index.css 文件中
'element-plus/theme-chalk/dark/css-vars.css' 文件中
3、vue2实现暗黑模式
3.1、实现
（1）建立一个暗黑主题样式文件：my-theme.css，并将其引入到main.js中
（2）my-theme.css文件中 自己根据chrome浏览器的样式工具进行调整了，html.dark为父选择器
示范：在my-theme.css 中根据需求调节出自己想要的样式
html.dark .el-submenu__title {background-color: #121212;color: #fff;
}html.dark .el-submenu__title:hover {background-color: #18222b;
}html.dark .el-menu--inline {background-color: #121212;color: #fff;
}html.dark .el-menu-item.is-active {color: var(--el-color-primary);
}html.dark .el-menu-item {background-color: #121212;color: #fff;
}html.dark .el-menu-item:hover {background-color: #18222b;
}html.dark .el-card {background-color: #121212;
}
（3）添加一个开关用于给html添加class="dark"选择器，也就是暗黑模式
<template><el-switch v-model="isDark" @change="changeMode" active-color="#13ce66" inactive-color="#ff4949"></el-switch>
</template><script>
export default {data() {return {isDark: false,}},methods: {// 模式切换changeMode(val) {// 获取html根元素标签let html = document.documentElementif (val) {// html添加class="dark"选择器html.classList.add('dark')} else {// html移除class="dark"选择器html.classList.remove('dark')}}}
}
</script>