Uncaught (in promise) ReferenceError: dom is not defined, babel

After doing many tutorials, they all explain differently, they served me as they explain in this tutorial
 medium.com/nodersec/webpack-babel-y-react-6b1f9353269
that is, I installed this

npm install --save react react-dom 
npm install --save-dev babel-core babel-loader babel-preset-es2015 babel-preset-react webpack webpack-dev-server 

and I made the imports as the tutorial says and you are ready

I do not know the context of what you're creating, but with seeing your code I think it should be like this:

import React from "react";
import ReactDOM from "react-dom";
export class V_admin extends React.Component {
    constructor() {
        super();
    }

    render() {
      return (
        <option>
           Hola mundo!
        </option>
    )
  }
}

ReactDOM.render(<V_admin/>, document.getElementById('root'))