Question

使用 ReactJS、Webpack 和 Babel 进行 Hello World

2018-10-15

581

reactjs npm webpack babeljs

我想用 React 打印简单的 Hello World。这是我的应用程序目录结构：

webpack.config.js

const path = require('path');

module.exports = {
    entry: {
        app: './js/app.js'
    },
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, 'build')
    },
    module: {
        loaders: [
            {
                test: /\.js$/,
                loader: 'babel-loader',
                query: {
                    presets: ['es2015', 'react']
                }
            }
        ]
    },
    stats: {
        colors: true
    },
    devtool: 'source-map'
};

js/app.js

var React = require('react');
var ReactDOM = require('react-dom');

ReactDOM.render(
    <h1>Hello, world!</h1>,
    document.getElementById('root')
  );

index.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <link href='http://fonts.googleapis.com/css?family=Roboto:400,300,700' rel='stylesheet' type='text/css'>
    <link href="css/styles.css" rel="stylesheet" type="text/css">
</head>
<body>
<div id="root"></div>
<script src="build/app.bundle.js"></script>
</body>
</html>

package.json

{
  "name": "es6-tutorial-react",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "webpack": "webpack --mode=development"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/ccoenraets/es6-tutorial-react.git"
  },
  "author": "",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com/ccoenraets/es6-tutorial-react/issues"
  },
  "homepage": "https://github.com/ccoenraets/es6-tutorial-react#readme",
  "devDependencies": {
    "@babel/core": "^7.1.2",
    "@babel/preset-env": "^7.1.0",
    "@babel/preset-react": "^7.0.0",
    "babel-core": "^6.26.3",
    "babel-loader": "^8.0.4",
    "babel-preset-es2015": "^6.24.1",
    "babel-preset-react": "^6.24.1",
    "react": "^16.5.2",
    "react-dom": "^16.5.2",
    "webpack": "^4.20.2",
    "webpack-cli": "^3.1.2"
  }
}

当我运行 npm run webpack 时，它返回错误：

Invalid configuration object. Webpack has been initialised using a configuration object that does not match the API schema. - configuration.module has an unknown property 'loaders'. These properties are valid: object { defaultRules?, exprContextCritical?, exprContextRecursive?, exprContextRegExp?, exprContextRequest?, noParse?, rules?, strictExportPresence?, strictThisContextOnImports?, unknownContextCritical?, unknownContextRecursive?, unknownContextRegExp?, unknownContextRequest?, unsafeCache?, wrappedContextCritical?, wrappedContextRecursive?, wrappedContextRegExp? } -> Options affecting the normal modules ( NormalModuleFactory ). npm ERR! code ELIFECYCLE npm ERR! errno 1 npm ERR! [email protected] webpack: webpack --mode=development npm ERR! Exit status 1 npm ERR! npm ERR! Failed at the [email protected] webpack script. npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in: npm ERR!
C:\Users\User\AppData\Roaming\npm-cache_logs\2018-10-15T10_57_59_640Z-debug.log

请。帮助谢谢。

Answer 1

正如 @Dominic 所说，使用 rules 属性，而不是立即使用 loaders 。如下所示：

...
module: {
   rules: [
     {
       test: /\.js$/,
       exclude: /(node_modules|bower_components)/,
       use: {
         loader: 'babel-loader',
         options: {
           presets: ['@babel/preset-env', '@babel/preset-react']
         }
       }
     }
   ]
 },
...

您需要修复的另一件事是您的 index.html ：

Change this: <script src="build/app.bundle.js"></script> 
To this: <script src="build/bundle.js"></script>

因为在您的 webpack.config.js 中，您已将输出文件名指定为 bunlde.js ，而不是 app.bundle.js 。

希望对您有所帮助！

Answer 2

您正在使用来自 webpack v3 的代码，但已安装 webpack v4。在 v4 中，Loaders 称为 rules 。请遵循最新指南： https://webpack.js.org/guides/getting-started/ 或 https://www.valentinog.com/blog/react-webpack-babel/ 等

您还安装了来自 @babel 的新预设，因此请确保您的 .babelrc 正确无误，并且不要遵循某些旧的 <= v6 指南。

Answer 3

降低版本，你的问题将得到解决。

"babel-cli": "^6.26.0",
"babel-core": "^6.26.3",
"babel-eslint": "^8.2.3",
"babel-loader": "^7.1.4",
"babel-preset-env": "^1.7.0",
"babel-preset-react": "^6.24.1",