They called Modal.

You can check the react-modal library.

Here is a simple example of react-modal being used in an app with some custom styles and focusable input elements within the modal content:

import React from 'react';
import ReactDOM from 'react-dom';
import Modal from 'react-modal';

const customStyles = {
  content : {
    top                   : '50%',
    left                  : '50%',
    right                 : 'auto',
    bottom                : 'auto',
    marginRight           : '-50%',
    transform             : 'translate(-50%, -50%)'
  }
};

// Make sure to bind modal to your appElement (http://reactcommunity.org/react-modal/accessibility/)
Modal.setAppElement('#yourAppElement')

class App extends React.Component {
  constructor() {
    super();

    this.state = {
      modalIsOpen: false
    };

    this.openModal = this.openModal.bind(this);
    this.afterOpenModal = this.afterOpenModal.bind(this);
    this.closeModal = this.closeModal.bind(this);
  }

  openModal() {
    this.setState({modalIsOpen: true});
  }

  afterOpenModal() {
    // references are now sync'd and can be accessed.
    this.subtitle.style.color = '#f00';
  }

  closeModal() {
    this.setState({modalIsOpen: false});
  }

  render() {
    return (
      <div>
        <button onClick={this.openModal}>Open Modal</button>
        <Modal
          isOpen={this.state.modalIsOpen}
          onAfterOpen={this.afterOpenModal}
          onRequestClose={this.closeModal}
          style={customStyles}
          contentLabel="Example Modal"
        >

          <h2 ref={subtitle => this.subtitle = subtitle}>Hello</h2>
          <button onClick={this.closeModal}>close</button>
          <div>I am a modal</div>
          <form>
            <input />
            <button>tab navigation</button>
            <button>stays</button>
            <button>inside</button>
            <button>the modal</button>
          </form>
        </Modal>
      </div>
    );
  }
}

ReactDOM.render(<App />, appElement);

You can see more examples here

Here is modern way to achieve this using React Hooks

import React, { useState } from "react";

const PopUp = ({ idMessage }) => {
  // create state `open` with default as false
  const [open, setOpen] = useState(false);
  return (
    <>
      {/* click of button toggles `open` value therefore visibility */}
      <button
        onClick={() => setOpen(!open)}
        type="button"
        className="btn btn-primary"
        data-toggle="modal"
        data-target={`#${idMessage}`}
      >
        {idMessage}
      </button>
      {/* If open is true show your <div /> */}
      {open && (
        <div
          className="modal fade"
          id={idMessage}
          tabIndex="-1"
          role="dialog"
          aria-labelledby="exampleModalLabel"
          aria-hidden="true"
        >
          content
        </div>
      )}
    </>
  );
};

export default PopUp;

You are on the right way!

Is it something you need? I prepared the example: click here

var Example = React.createClass({
    fbShare: function() {
        window.open('http://www.facebook.com/sharer.php?s=100&p[title]=Fb Share&p[summary]=Facebook share popup&p[url]=javascript:fbShare("http://jsfiddle.net/stichoza/EYxTJ/")&p[images][0]="http://jonbennallick.co.uk/wp-content/uploads/2012/08/Facebook-logo-ICON-02.png"', 'sharer', 'toolbar=0,status=0,width=548,height=325');
    },

    render: function() {
        return (<div>
            <img src="http://pasadenainstitute.com/fb-shareTransp122x42.png" onClick={this.fbShare} />
        </div>);
    }
});

ReactDOM.render(
    <Example />,
    document.getElementById('container')
);

isOpen is not a property of this, but of state. You have to write:

{this.state.isOpen && <Popup...

Here is the documentation in case you want to read about it yourself

To open the new window in an actual window, and not a tab, you need to pass in a specs parameter to window.open:

javascript:window.open('','_blank','height=600,width=400');