主要原理是利用webpack插件webpack-theme-color-replacer提取相关颜色css然后根据配置动态生成替换的css
具体实现步骤如下：
1.添加webpack插件，新建文件webpack/themePlugin.js

const ThemeColorReplacer = require('webpack-theme-color-replacer')
const forElementUI = require('webpack-theme-color-replacer/forElementUI')
const config = require('../src/config/appConfig')
module.exports = new ThemeColorReplacer({
    fileName: 'css/theme-colors.[contenthash:8].css',
    matchColors: [
        ...forElementUI.getElementUISeries(config.themeColor),  //element-ui主色系列
        // '#0cdd3a',  //自定义颜色
    ],
    changeSelector: forElementUI.changeSelector,
    isJsUgly:  process.env.NODE_ENV !== 'development',
    // injectCss: false,
    // resolveCss(resultCss) { // optional. Resolve result css code as you wish.
    //     return resultCss + youCssCode
    // }
})

matchColors数组中可配置多个自定义要替换的主题色
2.在vue.config.js中添加这个插件

const themePlugin=require('./webpack/themePlugin');
module.exports = {
 configureWebpack: {
    plugins: [
                themePlugin
             ]
    }
 }

3.新建文件themeColorClient.js

import client from 'webpack-theme-color-replacer/client'
import forElementUI from 'webpack-theme-color-replacer/forElementUI'
import appConfig from '@/config/appConfig'
export let curColor = appConfig.themeColor

// 动态切换主题色
export function changeThemeColor(newColor) {
    var options = {
        newColors: [...forElementUI.getElementUISeries(newColor)],
    }
    return client.changer.changeColor(options, Promise)
        .then(() => {
            curColor = newColor
            localStorage.setItem('theme_color', curColor)
        });
}

export function initThemeColor() {
    const savedColor = localStorage.getItem('theme_color')
    if (savedColor) {
        curColor = savedColor
        changeThemeColor(savedColor)
    }
}

4.在需要的时候调用 initThemeColor初始化颜色 changeThemeColor改变主题颜色

import { initThemeColor,changeThemeColor } from './utils/themeColorClient'
initThemeColor()
changeThemeColor('#F56C6C')//传入颜色格式应该为十六进制颜色值，'red'类似颜色暂不支持

具体细节请参考https://github.com/hzsrc/vue-...