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Version: 4.x

Client usage with bundlers

You will find below the configuration for bundling the client library with different bundlers:

Webpack 5​

Documentation: https://webpack.js.org/concepts/

Browser​

Installation:

npm i -D socket.io-client webpack webpack-cli babel-loader @babel/core @babel/preset-env \
    @babel/plugin-transform-object-assign webpack-remove-debug

webpack.config.js

module.exports = {
  entry: "./index.js",
  output: {
    filename: "bundle.js",
  },
  mode: "production",
  node: false,
  module: {
    rules: [
      {
        test: /\.m?js$/,
        use: {
          loader: "babel-loader",
          options: {
            presets: ["@babel/preset-env"], // ensure compatibility with older browsers
            plugins: ["@babel/plugin-transform-object-assign"], // ensure compatibility with IE 11
          },
        },
      },
      {
        test: /\.js$/,
        loader: "webpack-remove-debug", // remove "debug" package
      },
    ],
  },
};

For reference, here is the output of the webpack-bundle-analyzer package:

Output of the webpack-bundle-analyzer package

Node.js​

To use the client in a Node.js environment (server to server connection), here is the configuration:

Installation:

npm i -D socket.io-client webpack webpack-cli

webpack.config.js

module.exports = {
  entry: "./index.js",
  output: {
    filename: "bundle.js",
  },
  mode: "production",
  target: "node",
  externals: {
    bufferutil: "bufferutil",
    "utf-8-validate": "utf-8-validate",
  },
};

Note: without setting target: "node", you will likely encounter the following error:

ReferenceError: document is not defined

Rollup.js​

Documentation: https://rollupjs.org/guide/en/

Browser​

Installation:

npm i -D socket.io-client rollup @rollup/plugin-node-resolve @rollup/plugin-commonjs @rollup/plugin-commonjs \
  @rollup/plugin-babel rollup-plugin-uglify babel @babel/core @babel/preset-env

rollup.config.js

import resolve from "@rollup/plugin-node-resolve";
import commonjs from "@rollup/plugin-commonjs";
import babel from "@rollup/plugin-babel";
import { uglify } from "rollup-plugin-uglify";

export default {
  input: "index.js",
  output: {
    file: "bundle.js",
    format: "cjs",
  },
  plugins: [
    resolve({
      browser: true,
    }),
    commonjs(),
    babel({
      include: ["**.js", "node_modules/**"],
      babelHelpers: "bundled",
      presets: ["@babel/preset-env"],
    }),
    uglify(),
  ],
};

Node.js​

Installation:

npm i -D socket.io-client rollup @rollup/plugin-node-resolve @rollup/plugin-commonjs rollup-plugin-uglify

rollup.config.js

import resolve from "@rollup/plugin-node-resolve";
import commonjs from "@rollup/plugin-commonjs";
import { uglify } from "rollup-plugin-uglify";

export default {
  input: "index.js",
  output: {
    file: "bundle.js",
    format: "cjs",
  },
  plugins: [
    resolve({
      preferBuiltins: true,
    }),
    commonjs(),
    uglify(),
  ],
};