Error: Cannot resolve module 'babel-loader'

问题

I'm trying to run webpack on my postinstall script in my package.json when I push to heroku but I am getting the following error.

ERROR in Entry module not found: Error: Cannot resolve module 'babel-loader' in /tmp/build_6cb4b10367d9382367ab72f2e2f33118

When I run the command locally I get no issues. Below is my webpack config - i have tried using resolveLoader to fix the resolving issue but to no avail?

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

var config = {
  entry: path.resolve(__dirname, './app/main.js'),
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'bundle.js'
  },
  module: {
    loaders: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        loader: 'babel-loader'
      },
      {
        test: /\.less$/,
        loader: 'style!css!less'
      }]
  },
  resolve: {
    extensions: ['', '.js', '.jsx', '.less'],
    modulesDirectories: [
      'node_modules'
    ]
  },
  resolveLoader: {
    root: path.resolve(__dirname, 'node_modules')
  },
  plugins: [
    new webpack.optimize.UglifyJsPlugin({minimize: true})
  ]
};

module.exports = config;

Any suggestions? Thanks

回答1:

I found out why. I didn't have babel or babel-core in my package.json. Add them fixed the error.

  "devDependencies": {
    "babel": "^5.8.23",
    "babel-core": "^5.0.0",
    "babel-loader": "^5.3.2"
}

回答2:

In my case, I had mis-spelled the loader while installing it, so make sure you install

babel-loader

NOT

bable-loader

回答3:

In my case, I tried the command:

$ npm install babel-loader --save

and continued to fix the rest based on the reminder from the console, and it fixed the issue:

"ERROR in Entry module not found: Error: Can't resolve 'babel-loader'"

回答4:

I'm using yarn and webpacker for a rails + react project.

I know not everyone can upgrade all their dependencies without breaking things, but for me, adding running yarn upgrade fixed this error.

That was with only @babel/core in my dependencies config, since babel-loader is included as a dependency of webpacker.

回答5:

In some cases, when deploying to production (for example with Rails Webpacker), dev dependencies are not loaded. So having babel-loader in devDependencies will not work.

In fact, it makes sense that babel-loader would be placed in dependencies, not devDependencies, because it's used in the production code itself. The only packages that should be in devDependencies are those that are run in development, such as tests and linters.