Blend React into your exising site by rendering elements inline, targeting an element by id.
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README.md

React Element Portal

travis

Render a React component inline, but target a DOM element (or elements) by id or selector.

Why?

If you're making a shiny new React app where you use React everywhere, for every page, and for the entirety of every page, then you probably don't need this. But if you live in an imperfect world, where you have a server-generated header/footer or some static blog pages, or anything else not fully controlled by React, you can use an ElementPortal to control those things from inside a single root React element.

Install

npm install react-element-portal --save

Usage with vanilla React

Let's say we get this from the server:

<html>
  <body>
    <!-- Header generated by server -->
    <div id="header">
      <a href="/">Home</a>
      <h1>My Sorta Cool App</h1>
      <div id="user">Joe</div>
    </div>
    <!-- Container for React to do its thing -->
    <div id="app"></div>
  </body>
</html>

Even though we don't control the header, we can pretend like parts of it are owned by a single React root element.

import ElementPortal from 'react-element-portal';

ReactDOM.render(
  // Just rendering a single React element.
  <div>
    {/* Use some React to spice up our header. */}
    <ElementPortal id="user">
      <div>
        <Menu>
          <Label>Joe</Label>
          <Items>
            <Item>Upgrade</Item>
            <Item>Settings</Item>
            <Item>Support</Item>
          </Items>
        </Menu>
      </div>
    </ElementPortal>
    {/* And render our main app as a sibling. */}
    <div>
      <h1>My App</h1>
      <p>This is my main app and gets rendered to #app.</p>
    </div>
  </div>,
  document.getElementById('app')
);

You can also use a selector instead of an id.

<ElementPortal selector=".header .user">
  <div>
    ...
  </div>
</ElementPortal>

Additional features

Reset styling

The resetAttributes prop can be used to remove any attributes from the DOM node we are rendering to:

// All styles and classes from the node with id "header" will be cleared
<ElementPortal id="header" resetAttributes={['class', 'style']}>
  <div className="some-other-class">
    ...
  </div>
</ElementPortal>

View property

ElementPortal also accepts an optional view prop that takes a component, to be rendered inside the portal:

<ElementPortal id="header" view={CoolHeaderComponent} />

One advantage of using the view prop is the ability to derive properties from the original DOM node and pass them to the the component.

Let's say our original DOM element already contains some useful data:

<div id="header" data-user-id="26742">
  Joe
</div>

And we would like to render the following component:

const CoolGreeting = ({ userId, name }) => (
  <div>Welcome <a href={`/profile/${userId}`}>{name}!</a></div>
)

By using the mapNodeToProps prop, you can easily pass this data like so:

import dataAttributes from 'data-attributes';

const mapNodeToProps = (node) => ({
  name: node.textContent,
  ...dataAttributes(node)
});

ReactDOM.render(
  <ElementPortal id="header" mapNodeToProps={mapNodeToProps} />,
  document.getElementById('app')
);

Usage as Higher Order Component

ElementPortal can also be used as a HOC:

import { withElementPortal } from 'react-element-portal';
import MyComponent from 'my-component';

const MyComponentWithPortal = withElementPortal(MyComponent);

ReactDOM.render(
  <MyComponentWithPortal id="user" />,
  document.getElementById('app')
);

or composing with other HOC's:

import { withElementPortal } from 'react-element-portal';
import { compose, connect } from 'react-redux';

const MyComponent = (props) => <h1>Hello, {props.name}!</h1>;

const MyComposedComponent = compose(
  withElementPortal,
  connect((state) => ({ name: state.name }))
)(MyComponent);

Passing context to your ElementPortal

Context from your main tree is passed down automatically to your ElementPortal. For example, if you use Redux, the store context will not get lost, and using connect will behave as expected in the children of your ElementPortal.