package.json

{
  "name": "tmp",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "webpack": "webpack",
    "dev": "webpack-dev-server --open"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@babel/core": "^7.4.5",
    "@babel/preset-react": "^7.0.0",
    "babel-loader": "^8.0.6",
    "react": "^16.8.6",
    "react-dnd": "^8.0.3",
    "react-dnd-html5-backend": "^8.0.3",
    "react-dom": "^16.8.6",
    "webpack": "^4.35.0",
    "webpack-cli": "^3.3.5"
  },
  "devDependencies": {
    "@babel/preset-env": "^7.4.5",
    "webpack-dev-server": "^3.7.2"
  }
}

index.html

<!doctype html>
<html>
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<div id="root"></div>
<script type="text/javascript" src="/build/index.js"></script>
</body>
</html>

.babelrc

{  "presets": ["@babel/preset-env", "@babel/preset-react"]}

webpack.config.js

const path = require('path');

module.exports = {
    entry: path.join(__dirname, 'src', 'index.js'),
    output: {
        path: path.resolve(__dirname, 'build'),
        publicPath: 'build/',
        filename: 'index.js'
    },
    module: {
        rules: [{
            test: /\.js$/,
            loader: 'babel-loader',
            exclude: '/node_modules/'
        }
        ]
    }
};