对于开发者来说，可能需要针对不同端做一些特殊的逻辑，因此也就需要一个方法来判断区分不同的环境。kbone 推荐的做法是通过 webpack 注入一个环境变量：
// webpack.mp.config.js module.exports = { plugins: [ new webpack.DefinePlugin({ 'process.env.isMiniprogram': true, }), // ... other options ], // ... other options }后续在业务代码中，就可以通过 process.env.isMiniprogram 来判断是否在小程序环境：
if (process.env.isMiniprogram) { console.log('in miniprogram') } else { console.log('in web') }在 kbone-advanced 目录下创建 01-env 目录，本案例在这个目录下完成。
编辑 package.json：
{ "name": "01-env", "version": "1.0.0", "description": "", "main": "index.js", "scripts": { "build": "rimraf dist/web && cross-env NODE_ENV=production webpack --config build/webpack.config.js --progress --hide-modules", "mp": "cross-env NODE_ENV=production webpack --config build/webpack.mp.config.js --progress --hide-modules" }, "dependencies": { "add": "^2.0.6", "vue": "^2.5.11" }, "browserslist": [ "> 1%", "last 2 versions", "not ie <= 8" ], "devDependencies": { "babel-core": "^6.26.0", "babel-loader": "^7.1.2", "babel-preset-env": "^1.6.0", "cross-env": "^5.0.5", "css-loader": "^0.28.7", "file-loader": "^1.1.4", "html-webpack-plugin": "^4.0.0-beta.5", "mini-css-extract-plugin": "^0.5.0", "optimize-css-assets-webpack-plugin": "^5.0.1", "stylehacks": "^4.0.3", "vue-loader": "^15.7.0", "vue-template-compiler": "^2.6.10", "webpack": "^4.29.6", "webpack-cli": "^3.2.3", "mp-webpack-plugin": "latest" }, "keywords": [], "author": "", "license": "ISC" }安装依赖包：
npm install在 01-env/build 目录下创建 webpack.config.js，内容如下：
var path = require('path') var MiniCssExtractPlugin = require('mini-css-extract-plugin') const { VueLoaderPlugin } = require('vue-loader') const HtmlWebpackPlugin = require('html-webpack-plugin') module.exports = { mode: 'production', entry: { index: path.resolve(__dirname, '../src/main.js'), }, output: { path: path.resolve(__dirname, '../dist/web/'), publicPath: './', filename: '[name].js' }, target: 'web', module: { rules: [ { test: /\.css$/, use: [ MiniCssExtractPlugin.loader, 'css-loader' ], }, { test: /\.vue$/, loader: 'vue-loader', }, { test: /\.js$/, use: { loader: 'babel-loader', options: { presets: ['env'] } }, exclude: /node_modules/ }, { test: /\.(png|jpg|gif|svg)$/, loader: 'file-loader', options: { name: '[name].[ext]?[hash]' } } ] }, resolve: { extensions: ['*', '.js', '.vue', '.json'] }, plugins: [ new MiniCssExtractPlugin({ filename: '[name].css' }), new VueLoaderPlugin(), new HtmlWebpackPlugin({ filename: 'index.html', chunks: ['index'], template: path.join(__dirname, '../index.html') }), ] }在 01-env/src 目录下创建 main.js，内容如下：
import Vue from 'vue' import App from './App' new Vue({ el: '#app', render: h => h(App) })在 01-env/src 目录下创建 App.vue，内容如下：
<template> <div> I am {{info}} </div> </template> <script> export default { computed: { info() { if (process.env.isMiniprogram) { return 'in miniprogram' } else { return 'in web' } } } } </script>在项目根目录下创建 index.html，内容如下：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no,minimal-ui, viewport-fit=cover" /> <meta content="yes"name="apple-mobile-web-app-capable"/> <meta content="black"name="apple-mobile-web-app-status-bar-style"/> <meta name="format-detection"content="telephone=no, email=no" /> <title>vue</title> <style type="text/css"> #app { font-family: 'Avenir', Helvetica, Arial, sans-serif; -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; text-align: center; color: #2c3e50; margin-top: 60px; } </style> </head> <body> <div id="app"></div> </body> </html>在 01-env/build 目录下创建 webpack.mp.config.js，内容如下：
const path = require('path') const webpack = require('webpack') const MiniCssExtractPlugin = require('mini-css-extract-plugin') const { VueLoaderPlugin } = require('vue-loader') const OptimizeCSSAssetsPlugin = require('optimize-css-assets-webpack-plugin'); const TerserPlugin = require('terser-webpack-plugin') const MpPlugin = require('mp-webpack-plugin') // 用于构建小程序代码的 webpack 插件 const isOptimize = false // 是否压缩业务代码，开发者工具可能无法完美支持业务代码使用到的 es 特性，建议自己做代码压缩 module.exports = { mode: 'production', entry: { 'app': path.resolve(__dirname, '../src/main.mp.js') }, output: { path: path.resolve(__dirname, '../dist/mp/common'), // 放到小程序代码目录中的 common 目录下 filename: '[name].js', // 必需字段，不能修改 library: 'createApp', // 必需字段，不能修改 libraryExport: 'default', // 必需字段，不能修改 libraryTarget: 'window', // 必需字段，不能修改 }, target: 'web', // 必需字段，不能修改 optimization: { runtimeChunk: false, // 必需字段，不能修改 splitChunks: { // 代码分隔配置，不建议修改 chunks: 'all', minSize: 1000, maxSize: 0, minChunks: 1, maxAsyncRequests: 100, maxInitialRequests: 100, automaticNameDelimiter: '~', name: true, cacheGroups: { vendors: { test: /[\\/]node_modules[\\/]/, priority: -10 }, default: { minChunks: 2, priority: -20, reuseExistingChunk: true } } }, minimizer: isOptimize ? [ // 压缩CSS new OptimizeCSSAssetsPlugin({ assetNameRegExp: /\.(css|wxss)$/g, cssProcessor: require('cssnano'), cssProcessorPluginOptions: { preset: ['default', { discardComments: { removeAll: true, }, minifySelectors: false, // 因为 wxss 编译器不支持 .some>:first-child 这样格式的代码，所以暂时禁掉这个 }], }, canPrint: false }), // 压缩 js new TerserPlugin({ test: /\.js(\?.*)?$/i, parallel: true, }) ] : [], }, module: { rules: [ { test: /\.css$/, use: [ MiniCssExtractPlugin.loader, 'css-loader' ], }, { test: /\.vue$/, loader: [ 'vue-loader', ], }, { test: /\.js$/, use: { loader: 'babel-loader', options: { presets: ['env'] } }, exclude: /node_modules/ }, { test: /\.(png|jpg|gif|svg)$/, loader: 'file-loader', options: { name: '[name].[ext]?[hash]' } } ] }, resolve: { extensions: ['*', '.js', '.vue', '.json'] }, plugins: [ new webpack.DefinePlugin({ 'process.env.isMiniprogram': true, // 注入环境变量，用于业务代码判断 }), new MiniCssExtractPlugin({ filename: '[name].wxss', }), new VueLoaderPlugin(), new MpPlugin(require('./miniprogram.config.js')), ], }在 01-env/src 下创建 main.mp.js 文件，内容如下：
import Vue from 'vue' import App from './App' export default function createApp() { const container = document.createElement('div') container.id = 'app' document.body.appendChild(container) return new Vue({ el: '#app', render: h => h(App) }) }