Build create-react-app to a single file. Useful for things like WordPress plugins.

build-non-split.js

const rewire = require('rewire');
const defaults = rewire('react-scripts/scripts/build.js');
let config = defaults.__get__('config');

config.optimization.splitChunks = {
  cacheGroups: {
    default: false,
  },
};

config.optimization.runtimeChunk = false;

package.json

{
  "name": "cra",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "http-proxy-middleware": "^0.19.1",
    "node-sass": "^4.13.0",
    "react": "^16.8.4",
    "react-dom": "^16.8.4",
    "react-router-dom": "^4.3.1",
    "react-scripts": "2.1.8",
    "rewire": "^4.0.1"
  },
  "homepage": "/wp-content/plugins/plugin/path/to/crabuilddir",
  "scripts": {
    "start": "react-scripts start",
    "build2": "react-scripts build",
    "build": "node ./scripts/build-non-split.js",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": [
    ">0.2%",
    "not dead",
    "not ie <= 11",
    "not op_mini all"
  ]
}