反应，wepack，babel，节点，npm启动错误

Question

ERROR in ./main.js

Module build failed (from ./node_modules/babel-loader/lib/index.js):

Error: Cannot find module '@babel/preset-es2015' from 'F:\\reactapp'
at Function.module.exports [as sync] (F:\\reactapp\\node_modules\\resolve\\lib\\sync.js:43:15)
at resolveStandardizedName (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\files\\plugins.js:101:31)
at resolvePreset (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\files\\plugins.js:58:10)
at loadPreset (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\files\\plugins.js:77:20)
at createDescriptor (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\config-descriptors.js:154:9)
at items.map (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\config-descriptors.js:109:50)
at Array.map () at createDescriptors (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\config-descriptors.js:109:29)
at createPresetDescriptors (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\config-descriptors.js:101:10)
at passPerPreset (F:\\reactapp\\node_modules@babel\\core\\lib\\config\\config-descriptors.js:58:96)
@ multi (webpack)-dev-server/client?http://localhost:8080 (webpack)/hot/dev-server.js ./main.js main[2]

Child html-webpack-plugin for "index.html":
1 asset
Entrypoint undefined = index.html
[./node_modules/html-webpack-plugin/lib/loader.js!./index.html] 448 bytes {0} [built]
[./node_modules/lodash/lodash.js] 527 KiB {0} [built]
[./node_modules/webpack/buildin/global.js] (webpack)/buildin/global.js 472 bytes {0} [built] [./node_modules/webpack/buildin/module.js] (webpack)/buildin/module.js 497 bytes {0} [built]

i ?wdm?: Failed to compile.

Terminate batch job (Y/N)?

package.json file:

package json file is as follows. I followed https://www.tutorialspoint.com/reactjs/reactjs_environment_setup.htm

{
  "name": "reactapp",
  "version": "1.0.0",
  "description": "demo project",
  "main": "index.js",
  "scripts": {
    "start": "webpack-dev-server --mode development --open --hot",
    "build": "webpack --mode production"
  },
  "keywords": [
    "[]"
  ],
  "author": "manjunathan g",
  "license": "ISC",
  "dependencies": {
    "@babel/cli": "^7.2.3",
    "@babel/core": "^7.2.2",
    "@babel/preset-react": "^7.0.0",
    "react": "^16.7.0",
    "react-dom": "^16.7.0",
    "webpack": "^4.28.2",
    "webpack-cli": "^3.1.2",
    "webpack-dev-server": "^3.1.14"
  },
  "devDependencies": {
    "@babel/plugin-proposal-class-properties": "^7.2.3",
    "@babel/preset-env": "^7.2.3",
    "babel-core": "^6.26.3",
    "babel-loader": "^8.0.4",
    "babel-preset-env": "^1.7.0",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "html-webpack-plugin": "^3.2.0"
  }
}

babel config:

Babel config file is as below; followed as per https://www.tutorialspoint.com/reactjs/reactjs_environment_setup.htm

{
  "presets":["env", "react"]
}

webpack config

webpack config is as follows:

const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
   entry: './main.js',
   output: {
      path: path.join(__dirname, '/bundle'),
      filename: 'index_bundle.js'
   },
   devServer: {
      inline: true,
      port: 8080
   },
   module: {
      rules: [
         {
            test: /\.jsx?$/,
            exclude: /node_modules/,
            loader: 'babel-loader',
            query: {
               presets: ['@babel/react', '@babel/es2015'],
               plugins: ['@babel/proposal-class-properties']
            }
         }
      ]
   },
   plugins:[
      new HtmlWebpackPlugin({
         template: './index.html'
      })
   ]
}

Answer 1

The @babel/preset-es2015 package has been deprecated and you can no longer install it from NPM.

The recommendation now is to use @babel/preset-env instead.

Answer 2

There are a lot of mistakes in your file configuration. Let me try to solve it:

.babelrc

You don't need the following devDependencies: babel-core , babel-preset-env , babel-preset-react and babel-preset-es2015 . They are deprecated since Babel 7 was realeased. Substitute your code to this:

{
    "presets": ["@babel/preset-env", "@babel/preset-react"]
}

webpack.config.js

Since webpack 4 was released, you don't need to inform the entry and output fields (You can do it for custom configurations). By default, webpack will look for index.js file located in the src/ directory (this directory must be in the root of your project). Webpack will create the module dependency graph from this file and output the bundled file to the dist/ directory. Try to configure your webpack.config.js like this:

const path = require("path")
const HtmlWebpackPlugin = require("html-webpack-plugin")

module.exports = {
    module: {
        rules: [
            {
                test: /\.jsx$/,
                exclude: /node_modules/,
                use: { loader: "babel-loader" }
            },
            {
                test: /\.html$/,
                use: { loader: "html-loader" } //Install it: 'npm i -D html-loader'
            }
        ]
    },
    plugins: [
         new HtmlWebpackPlugin({
              template: "src/index.html" // Put the index.html in the src/ directory
         })
    ]
}

I'm not an expert in configuring webpack and I don't know if I could help you. I wrote an article on medium setting the environment to work with react, babel and webpack, but it is in portuguese . If you want to check: https://medium.com/@brunonakayabu/react-webpack-e-babel-configurando-o-ambiente-de-desenvolvimento-c7ee8a994222