Webpack-您可能需要适当的加载器

问题描述

每次我重新使用JavaScript时，都会遇到webpack和transpiler的困扰。我在这里需要帮助，我被困住了。即使指定了Webpack，也找不到合适的加载器。

webpack.config.js

const path = require( "path" );

module.exports = {
    entry: "./app.js",output: {
        filename: "starmap.js",path: path.resolve(__dirname,"../asset/js/" )
    },mode : "development",module : {
        rules : [
            {
                test: /\\.js$/,exclude: /node_modules/,loader: "babel-loader",options: {
                    presets: [ "@babel/preset-env","@babel/preset-react" ]
                }
            }
        ]
    }
}

package.json

{
  "name": "editor","version": "1.0.0","description": "","main": "app.js","scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },"keywords": [],"author": "","license": "ISC","dependencies": {
    "react": "^17.0.0","react-dom": "^17.0.0"
  },"devDependencies": {
    "@babel/cli": "^7.12.1","@babel/core": "^7.12.3","@babel/preset-env": "^7.12.1","@babel/preset-react": "^7.12.1","@webpack-cli/init": "^1.0.2","babel-loader": "^8.1.0","babel-plugin-Syntax-dynamic-import": "^6.18.0","css-loader": "^5.0.0","style-loader": "^2.0.0","terser-webpack-plugin": "^5.0.0","webpack": "^5.1.3","webpack-cli": "^4.1.0"
  }
}

app.js

import React from "react"
import { render } from "react-dom"

class Starmap extends React.Component {
    constructor() {
        super()
        this.state = []
    }

    render() {
        return "Hello world"
    }
}

render( <Starmap />,document.getElementById("customizer"))

.babelrc

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

运行webpack时出现此错误：

ERROR in ./app.js 15:8
Module parse Failed: Unexpected token (15:8)
You may need an appropriate loader to handle this file type,currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
| }
| 
> render( <Starmap />,document.getElementById("_customizer"))

但是成功运行npx babel app.js转码。我的webpack配置有问题，我已经仔细观察了，一切似乎还可以。

解决方法

似乎您的js未被babel-loader处理。我相信问题出在您的测试正则表达式中

更改

test: /\\.js$/,

到

test: /\.js$/,