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Bundler Polyfill Issues - Webpack 5

While setting up a new web3 project from scratch, you might face multiple issues the bundler. This issue is due to the fact that core packages like eccrypto have certain dependencies which are not present within the build environment. Webpack 5 especially introduced a lot of issues since it does not include many of these packages by default. The go-to method for rectifying these issues has been to simply add the missing modules directly into the package, and edit the bundler configuration to take advantage of that.

Although this method works, it increases the bundle size significantly, causing slow loading speeds and a bad user experience. It is important to note that these modules, even while the build fails, are still present within the browser environment. Many libraries like Web3Auth are written in a way so as to take advantage of this fact. Hence, even if the build doesn't contain the polyfill, the library should still work as expected. However, if you are using a library which does not take advantage of this fact, you might face issues while using the library.

Hence, you need to be mindful of the fact that you only require certain node polyfills to be added to your project, while testing each of it's functionalities. At the same time, you need to tell the bundler to ignore the missing modules, and not include them in the build.

In this guide, we have added instructions of adding the polyfills of some of the most commonly used web frameworks:

React (create-react-app)​

  • Install react-app-rewired into your application
npm install --save-dev react-app-rewired
  • Check for the missing libraries in your build and included packages, and accordingly polyfill them. For Web3Auth, you just need to polyfill the buffer and process libraries
npm install --save-dev buffer process
warning

There might be a possibility that you might need to polyfill more libraries, in case you're using any other blockchain library alongside Web3Auth that requires them. Generally the libraries like crypto-browserify, stream-browserify, browserify-zlib, assert, stream-http, https-browserify, os-browserify, url are the ones that might be required. crypto-browserify and stream-browserify being the most common polyfills.

  • Create config-overrides.js in the root of your project folder with the content:
const webpack = require("webpack");

module.exports = function override(config) {
  const fallback = config.resolve.fallback || {};
  Object.assign(fallback, {
    crypto: false, // require.resolve("crypto-browserify") can be polyfilled here if needed
    stream: false, // require.resolve("stream-browserify") can be polyfilled here if needed
    assert: false, // require.resolve("assert") can be polyfilled here if needed
    http: false, // require.resolve("stream-http") can be polyfilled here if needed
    https: false, // require.resolve("https-browserify") can be polyfilled here if needed
    os: false, // require.resolve("os-browserify") can be polyfilled here if needed
    url: false, // require.resolve("url") can be polyfilled here if needed
    zlib: false, // require.resolve("browserify-zlib") can be polyfilled here if needed
  });
  config.resolve.fallback = fallback;
  config.plugins = (config.plugins || []).concat([
    new webpack.ProvidePlugin({
      process: "process/browser",
      Buffer: ["buffer", "Buffer"],
    }),
  ]);
  config.ignoreWarnings = [/Failed to parse source map/];
  config.module.rules.push({
    test: /\.(js|mjs|jsx)$/,
    enforce: "pre",
    loader: require.resolve("source-map-loader"),
    resolve: {
      fullySpecified: false,
    },
  });
  return config;
};
  • Within package.json change the scripts field for start, build and test. Instead of react-scripts replace it with react-app-rewired
"scripts": {
    "start": "react-app-rewired start",
    "build": "react-app-rewired build",
    "test": "react-app-rewired test",
    "eject": "react-scripts eject"
},

The missing Nodejs polyfills should be included now and your app should be functional with web3.

note

If you're using craco, similar changes need to be made to craco.config.js

Angular​

  • Check for the missing libraries in your build and included packages, and accordingly polyfill them. For Web3Auth, you just need to polyfill the buffer and process libraries. For the rest of the libraries, we are installing a dummy module called empty-module which helps us get rid of the warnings while building the project.
npm install --save-dev buffer process empty-module
warning

There might be a possibility that you might need to polyfill more libraries, in case you're using any other blockchain library alongside Web3Auth that requires them. Generally the libraries like crypto-browserify, stream-browserify, browserify-zlib, assert, stream-http, https-browserify, os-browserify, url are the ones that might be required. crypto-browserify and stream-browserify being the most common polyfills.

  • Within tsconfig.json add the following paths in compilerOptions so Webpack can get the correct dependencies
{
  "compilerOptions": {
    "paths" : {
      "crypto": ["./node_modules/empty-module"], // crypto-browserify can be polyfilled here if needed
      "stream": ["./node_modules/empty-module"], // stream-browserify can be polyfilled here if needed
      "assert": ["./node_modules/empty-module"], // assert can be polyfilled here if needed
      "http": ["./node_modules/empty-module"], // stream-http can be polyfilled here if needed
      "https": ["./node_modules/empty-module"], // https-browserify can be polyfilled here if needed
      "os": ["./node_modules/empty-module"], // os-browserify can be polyfilled here if needed
      "url": ["./node_modules/empty-module"], // url can be polyfilled here if needed
      "zlib": ["./node_modules/empty-module"], // browserify-zlib can be polyfilled here if needed
      "process": ["./node_modules/process"],
    }
  }
}
  • Add the following lines to polyfills.ts file:
(window as any).global = window;
global.Buffer = global.Buffer || require("buffer").Buffer;
global.process = global.process || require("process");

Vue.js​

  • Check for the missing libraries in your build and included packages, and accordingly polyfill them. For Web3Auth, you just need to polyfill the buffer and process libraries
npm install --save-dev buffer process
warning

There might be a possibility that you might need to polyfill more libraries, in case you're using any other blockchain library alongside Web3Auth that requires them. Generally the libraries like crypto-browserify, stream-browserify, browserify-zlib, assert, stream-http, https-browserify, os-browserify, url are the ones that might be required. crypto-browserify and stream-browserify being the most common polyfills.

  • Add the following lines to vue.config.js
const { defineConfig } = require("@vue/cli-service");
const { ProvidePlugin } = require("webpack");
const { BundleAnalyzerPlugin } = require("webpack-bundle-analyzer");
module.exports = defineConfig({
  transpileDependencies: true,
  lintOnSave: false,
  configureWebpack: (config) => {
    config.devtool = "source-map";
    config.resolve.symlinks = false;
    config.resolve.fallback = {
      crypto: false, // crypto-browserify can be polyfilled here if needed
      stream: false, // stream-browserify can be polyfilled here if needed
      assert: false, // assert can be polyfilled here if needed
      os: false, // os-browserify can be polyfilled here if needed
      https: false, // https-browserify can be polyfilled here if needed
      http: false, // stream-http can be polyfilled here if needed
      url: "url", // url is needed if using `signer.provider.send` method for signing from ethers.js
      zlib: false, // browserify-zlib can be polyfilled here if needed
    };
    config.plugins.push(new ProvidePlugin({ Buffer: ["buffer", "Buffer"] }));
    config.plugins.push(new ProvidePlugin({ process: ["process/browser"] }));
    config.plugins.push(
      new BundleAnalyzerPlugin({
        analyzerMode: "disabled",
      }),
    );
  },
});

Gatsby​

Can’t resolve object.assign/polyfill ?​

  • Check for the missing libraries in your build and included packages, and accordingly polyfill them. For Web3Auth, you just need to polyfill the buffer and process libraries
npm install --save-dev buffer process
warning

There might be a possibility that you might need to polyfill more libraries, in case you're using any other blockchain library alongside Web3Auth that requires them. Generally the libraries like crypto-browserify, stream-browserify, browserify-zlib, assert, stream-http, https-browserify, os-browserify, url are the ones that might be required. crypto-browserify and stream-browserify being the most common polyfills.

  • Add the following lines to gatsby-node.js
exports.onCreateWebpackConfig = ({ actions, plugins, getConfig }) => {
  const webpack = require("webpack");
  const path = require("path");
  const config = getConfig();
  if (config.externals && config.externals[0]) {
    config.externals[0]["node:crypto"] = require.resolve("crypto-browserify");
  }
  actions.setWebpackConfig({
    ...config,
    resolve: {
      fallback: {
        crypto: false,
        stream: false,
        assert: require.resolve("assert/"),
        http: false,
        https: false,
        os: false,
        url: false,
        zlib: false,
        "object.assign/polyfill": path.resolve("./node_modules/object.assign/polyfill.js"),
      },
    },
    plugins: [
      plugins.provide({ process: "process/browser" }),
      new webpack.ProvidePlugin({
        Buffer: ["buffer", "Buffer"],
      }),
    ],
  });
};