运行webpack4.* 打包报错：The ‘mode’ option has not been set

打包报如下错误：The ‘mode’ option has not been set, webpack will fallback to ‘production’ for this value. Set ‘mode’ option to ‘development’ or ‘production’ to enable defaults for each environment.

解决：配置如下

{
  "name": "public",
  "version": "1.0.0",
  "description": "",
  "main": "./src/main.js",
  "dependencies": {
    "lodash": "^4.17.15"
  },
  "devDependencies": {
    "webpack": "^4.42.1",
    "webpack-cli": "^3.3.11"
  },
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "dev": "webpack-dev-server --open --mode development",
    "build": "webpack --mode production"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"
}

package.json

const path = require('path');

module.exports = {
    entry: './src/main.js',
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, 'dist')
    },
    mode: 'development' // 设置mode
};

webpack.config.js

然后根目录下运行 .\node_modules\.bin\webpack  或者 全局  运行  webpack