Webpack Express Cannot Resolve Module 'fs', Request Dependency is Expression

Question

When I include Express in my project I always get these errors when I try to build with webpack.

webpack.config.dev.js

var path = require("path")

module.exports = {
  entry: {
    "server": "./server/server.ts"
  },
  output: {
    path: path.resolve(__dirname, "dist"),
    filename: "bundle.js",
    publicPath: "/public/"
  },
  module: {
    loaders: [
      {
        test: /\.ts(x?)$/,
        exclude: /node_modules/,
        loader: "ts-loader"
      }, {
        test: /\.js(x?)$/,
        exclude: /node_modules/,
        loader: "babel-loader"
      }, {
        test: /\.json$/,
        loader: "json-loader"
      }, {
        test: /\.scss$/,
        exclude: /node_modules/,
        loaders: ["style-loader", "css-loader", "postcss-loader", "sass-loader"]
      }, {
        test: /\.css$/,
        loader: ["style-loader", "css-loader", "postcss-loader"]
      }, {
        test: /\.(jpe?g|gif|png|svg)$/i,
        loader: 'url-loader?limit=10000'
      }
    ]
  }
}

I've tried:

1. Installing 'fs' but it doesn't work

2. Read somewhere to change the node fs property. It removes the error warnings but I don't think this is a good permanent solution.

   module.exports = {
     node: {
       fs: "empty"
     }
   }
   

   Time: 2496ms Asset Size Chunks Chunk Names bundle.js 761 kB 0 [emitted] server bundle.js.map 956 kB 0 [emitted] server + 119 hidden modules

   WARNING in ./~/express/lib/view.js Critical dependencies: 78:29-56 the request of a dependency is an expression @ ./~/express/lib/view.js 78:29-56 ERROR in ./~/express/lib/view.js

   Module not found: Error: Cannot resolve module 'fs' in /Users/clementoh/Desktop/boilerplate2/node_modules/express/lib @ ./~/express/lib/view.js 18:9-22 ERROR in ./~/send/index.js

   Module not found: Error: Cannot resolve module 'fs' in /Users/clementoh/Desktop/boilerplate2/node_modules/send @ ./~/send/index.js 24:9-22 ERROR in ./~/etag/index.js

   Module not found: Error: Cannot resolve module 'fs' in /Users/clementoh/Desktop/boilerplate2/node_modules/etag @ ./~/etag/index.js 22:12-25 ERROR in ./~/destroy/index.js

   Module not found: Error: Cannot resolve module 'fs' in /Users/clementoh/Desktop/boilerplate2/node_modules/destroy @ ./~/destroy/index.js 14:17-30 ERROR in ./~/mime/mime.js

   Module not found: Error: Cannot resolve module 'fs' in /Users/clementoh/Desktop/boilerplate2/node_modules/mime @ ./~/mime/mime.js 2:9-22

Answer 1

Adding "target": "node", works by adding it to the webpack.config.js.

Answer 2

Working Solution/Hack/Patch for Angular V6 and up

The solution for me was to hack the Angular-CLI module to spoof the missing node modules.

After installing locate the following file:

node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/browser.js

Find the node line and add this:

node: { crypto: true, stream: true, fs: 'empty', net: 'empty' }

And that's it!!!

🎉🎉🎉🎉🎉

Note: You will need to do this patch every time you update the package. So use this script:

package.json

"scripts": {
  ...
  "postinstall": "node patch-webpack.js"
  ...
}

patch-webpack.js

const fs = require('fs');
const f = 'node_modules/@angular-devkit/build-angular/src/angular-cli-files/models/webpack-configs/browser.js';

fs.readFile(f, 'utf8', function (err,data) {
  if (err) {
    return console.log(err);
  }
  let result = data.replace(/node: false/g, "node: {crypto: true, stream: true, fs: 'empty', net: 'empty'}");

  fs.writeFile(f, result, 'utf8', function (err) {
    if (err) return console.log(err);
  });
});

Source: https://blog.lysender.com/2018/07/angular-6-cannot-resolve-crypto-fs-net-path-stream-when-building-angular/

Answer 3

I added node: { fs: 'empty' } without luck,

then I added --config to start command:

webpack-dev-sever webpack.config.dev.js

Use --config flag to use the custom file.

webpack-dev-sever --config webpack.config.dev.js

Answer 4

I solved this problem by two steps:

1. Delete node_modules directory

2. Add target:'node' into webpack config file

Then run npm install. It worked for me fine.

Answer 5

I am on a stack Angular 2 - Electron - Webpack and I needed to use fs into my service, I finally found how to do :

1) inside your webpack.common.js, specify target:'electron-renderer'

2) inside your service or component : import * as fs from 'fs'; and use fs as would do for a node project.

Hope it help !

Answer 6

Just posting an answer, since not everyone reads comments on SO. @Aurora0001 nailed it. Webpack's config needs to have this set:

"target": "node"