“You may need an appropriate loader to handle this file type” with Webpack and Babel

问题

I am trying to use Webpack with Babel to compile ES6 assets, but I am getting the following error message:

You may need an appropriate loader to handle this file type.
| import React from 'react';
| /*
| import { render } from 'react-dom'

Here is what my Webpack config looks like:

var path = require('path');
var webpack = require('webpack');

module.exports = {
  entry: './index',
  output: {
    path: path.join(__dirname, 'dist'),
    filename: 'bundle.js',
    publicPath: '/dist/'
  },
  module: {
    loaders: [
      {
        test: /\.jsx?$/,
        loader: 'babel-loader',
        exclude: /node_modules/
      }
    ]
  }
}

Here is the middleware step that makes use of Webpack:

var webpack = require('webpack');
var webpackDevMiddleware = require('webpack-dev-middleware');
var config = require('./webpack.config');

var express = require('express');
var app = express();
var port = 3000;

var compiler = webpack(config);
app.use(webpackDevMiddleware(compiler, {
  noInfo: true,
  publicPath: config.output.publicPath
}));

app.get('/', function(req, res) {
  res.sendFile(__dirname + '/index.html');
});

app.listen(port, function(err) {
  console.log('Server started on http://localhost:%s', port);
});

All my index.js file is doing is importing react, but it seems like the 'babel-loader' is not working.

I am using 'babel-loader' 6.0.0.

回答1:

You need to install the es2015 preset:

npm install babel-preset-es2015

and then configure babel-loader:

{
    test: /\.jsx?$/,
    loader: 'babel-loader',
    exclude: /node_modules/,
    query: {
        presets: ['es2015']
    }
}

回答2:

Make sure you have the es2015 babel preset installed.

An example package.json devDependencies is:

"devDependencies": {
  "babel-core": "^6.0.20",
  "babel-loader": "^6.0.1",
  "babel-preset-es2015": "^6.0.15",
  "babel-preset-react": "^6.0.15",
  "babel-preset-stage-0": "^6.0.15",
  "webpack": "^1.9.6",
  "webpack-dev-middleware": "^1.2.0",
  "webpack-hot-middleware": "^2.0.0"
},

Now configure babel-loader in your webpack config:

{ test: /\.js$/, loader: 'babel-loader', exclude: /node_modules/ }

add a .babelrc file to the root of your project where the node modules are:

{
  "presets": ["es2015", "stage-0", "react"]
}

More info:

• babeljs.io - using babel with webpack

• babeljs.io - docs on .babelrc

• react-webpack-cookbook - configure react with webpack

• a react-webpack-example repo

回答3:

If you are using Webpack > 3 then you only need to install babel-preset-env, since this preset accounts for es2015, es2016 and es2017.

var path = require('path');
let webpack = require("webpack");

module.exports = {
    entry: {
        app: './app/App.js',
        vendor: ["react","react-dom"]
    },
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, '../public')
    },
    module: {
        rules: [{
            test: /\.jsx?$/,
            exclude: /node_modules/,
            use: {
                loader: 'babel-loader?cacheDirectory=true',
            }
        }]
    }
};

This picks up its configuration from my .babelrc file:

{
    "presets": [
        [
            "env",
            {
                "targets": {
                    "browsers":["last 2 versions"],
                    "node":"current"
                }
            }
        ],["react"]
    ]
}

回答4:

Due to updates and changes overtime, version compatibility start causing issues with configuration.

Your webpack.config.js should be like this you can also configure how ever you dim fit.

var path = require('path');
var webpack = require("webpack");

module.exports = {
  entry: './src/js/app.js',
  devtool: 'source-map',
    mode: 'development',
  module: {
    rules: [{
      test: /\.js$/,
      exclude: /node_modules/,
      use: ["babel-loader"]
    },{
      test: /\.css$/,
      use: ['style-loader', 'css-loader']
    }]
  },
  output: {
    path: path.resolve(__dirname, './src/vendor'),
    filename: 'bundle.min.js'
  }
};

Another Thing to notice it's the change of args, you should read babel documentation https://babeljs.io/docs/en/presets

.babelrc

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

NB: you have to make sure you have the above @babel/preset-env & @babel/preset-react installed in your package.json dependencies

回答5:

When using Typescript:

In my case I used the newer syntax of webpack v3.11 from their documentation page I just copied the css and style loaders configuration form their website. The commented out code (newer API) causes this error, see below.

  module: {
        loaders: [{
                test: /\.ts$/,
                loaders: ['ts-loader']
            },
            {
                test: /\.css$/,
                loaders: [
                    'style-loader',
                    'css-loader'
                ]
            }
        ]
        // ,
        // rules: [{
        //     test: /\.css$/,
        //     use: [
        //         'style-loader',
        //         'css-loader'
        //     ]
        // }]
    }

The right way is to put this:

    {
        test: /\.css$/,
        loaders: [
            'style-loader',
            'css-loader'
        ]
    }

in the array of the loaders property.

回答6:

This one throw me for a spin. Angular 7, Webpack I found this article so I want to give credit to the Article https://www.edc4it.com/blog/web/helloworld-angular2.html

What the solution is: //on your component file. use template as webpack will treat it as text template: require('./process.component.html')

for karma to interpret it npm install add html-loader --save-dev { test: /.html$/, use: "html-loader" },

Hope this helps somebody

来源：https://stackoverflow.com/questions/33469929/you-may-need-an-appropriate-loader-to-handle-this-file-type-with-webpack-and-b