react-to-webcomponent

react-to-webcomponent converts React components to custom elements! It lets you share react components as native elements that don't require being through React.

Basic Use

Given a react component like:

class Greeting extends React.Component {
  render() {
    return <h1>Hello, {this.props.name}</h1>;
  }
}

Call reactToWebComponent and customElements.define as follows:

import reactToWebComponent from "react-to-webcomponent";

const WebGreeting = reactToWebComponent(Greeting, React, ReactDOM);

customElements.define("web-greeting", WebGreeting);

Now you can use <web-greeting> like any other HTML element!

You can create it programatically:

const webGreeting = document.createElement("web-greeting");
webGreeting.name = "StandardsFan";

document.body.append(webGreeting);

webGreeting.innerHTML //-> "<h1>Hello, StandardsFan</h1>"

Or you can use it declaratively:

document.body.innerHTML = "<web-greeting></web-greeting>";

document.body.firstChild.name = "CoolBeans";

document.body.firstChild.innerHTML //-> "<h1>Hello, CoolBeans</h1>"

Working with Attributes

By default, custom elements created by reactToWebComponent only pass properties to the underlying React component. To make attributes work, you must specify your component's properties with PropTypes as follows:

class Greeting extends React.Component {
  render() {
    return <h1>Hello, {this.props.name}</h1>;
  }
}

Greeting.propTypes = {
  name: PropTypes.string.isRequired
};

Now reactToWebComponent will know to look for name attributes as follows:

document.body.innerHTML = "<web-greeting name='Amazed'></web-greeting>";

document.body.firstChild.innerHTML //-> "<h1>Hello, Amazed</h1>"

API

reactToWebComponent(ReactComponent, React, ReactDOM) takes the following:

• ReactComponent - A react component that you want to convert to a Web Component.
• React - A version of React (or preact-compat) the component works with.
• ReactDOM - A version of ReactDOM (or preact-compat) that the component works with.

A new class inheriting from HTMLElement is returned. This class can be directly passed to customElements.define as follows:

customElements.define("web-greeting",
    reactToWebComponent(Greeting, React, ReactDOM) );

Or the class can be defined and used later:

const WebGreeting = reactToWebComponent(Greeting, React, ReactDOM);

customElements.define("web-greeting", WebGreeting);

var myGreeting = new WebGreeting();
document.body.appendChild(myGreeting);

Or the class can be extended:

class WebGreeting extends reactToWebComponent(Greeting, React, ReactDOM)
{
    disconnectedCallback(){
        super.disconnectedCallback();
        // special stuff
    }
}
customElements.define("web-greeting", WebGreeting);

How it works

reactToWebComponent creates a constructor function whose prototype is a Proxy. This acts as a trap for any property set on instances of the custom element. When a property is set, the proxy:

• re-renders the React component inside the custom element.
• creates an enumerable getter / setter on the instance to save the set value and avoid hitting the proxy in the future.

Also:

• Enumerable properties and values on the custom element are used as the props passed to the React component.
• The React component is not rendered until the custom element is inserted into the page.