Transporting your Components Anywhere with React Portals
Tags: react, javascript, webdev, tutorial
Published: 2022-10-12 20:42:42

When we create components in React, normally they exist within the component tree. This is mostly fine, but sometimes we want certain parts of a component to appear **outside the component tree**, or somewhere entirely different. This is a common requirement when we create modal popup windows, which need to be above all other components. We may create these within a component, but ultimately we'll want them above everything else, and having them nested within many components can can cause issues as their `z-index` will fall below whatever they are within:

![React Component Diagram](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/7vz6wop4vehn76vy8ef7.png)


To solve this problem, we can **teleport** the modal out of its own component and into another part of our template using `createPortal`. This allows us to put our component anywhere we desire else, like the base of the HTML tree, inside the `body` tag, or inside another element. Even though the element exists within the component tree, `createPortal` gives us the power to put it anywhere we like.

## Using React Portals

To show you how portals work, consider we have the following basic React code inside our `App.js` file. Here, we want the modal to appear on top of everything else. As such, we've created a `div` called `#modal-container`. This is ultimately where we want all of our modals to go into:
```javascript
import logo from './logo.svg';
import './App.css';
import { useState } from 'react'
import Modal from './components/Modal.js';

function App() {
    const [isModalOpen, setIsModalOpen] = useState(false);
    return (
        <div className="App">
            <header className="App-header">
                <img src={logo} className="App-logo" alt="logo" />
                <p>
                Edit <code>src/App.js</code> and save to reload.
                </p>

                <button onClick={() => setIsModalOpen(!isModalOpen)}>
                    Click to Open Modal
                </button>
                <Modal modalState={isModalOpen} onClickEvent={() => setIsModalOpen(!isModalOpen)}>
                    This is Modal Content!
                </Modal>
            </header>
            <div id="modal-container"></div>
        </div>
    );
}

export default App;

```

Inside `App.js`, I've imported a component called `Modal`. This is our Modal component, which will pop up any time the user clicks the button. Whenever `isModalOpen` is set to true using `setIsModalOpen()`, the modal should appear. Otherwise, it'll disappear. 

I've also got a bit of CSS to ensure our modals do indeed appear on top of everything else:
```css
#modal-container {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 9999;
    height: 100%;
    pointer-events: none;
}

.modal {
    position: absolute;
    top: 200px;
    background: white;
    border-radius: 4px;
    left: calc(50% - 100px);
    width: 200px;
}
```

### Creating our portal

Creating a potal is pretty easy - there is one function, `createPortal()`. Instead of returning some DOM in React, we return the `Portal` instead. `createPortal()` accepts two arguments - the DOM element we want to return - in this case, the modal - and the DOM element we want to teleport our DOM element to. So our second argument is `document.getElementById('modal-container')`, since we want to put all of our modals into `#modal-container`:
```javascript
import { createPortal } from 'react-dom';

function Modal({modalState, onClickEvent}) {

    if(!modalState) return null;

    return (
        createPortal(
            <div className="modal">
                <button onClick={onClickEvent}>Close Modal</button>
                <div className="modal-content">Modal Content goes here</div>
            </div>, 
            document.getElementById('modal-container')
        )
    );
};

export default Modal;
```

Although we teleported our DOM element to `modal-container`, it still behaves like a normal React child. Since the Portal still exists in the React tree, features like the context the element is in still work the same. 

It should also be noted that although we have `modal-container` and `Modal` in the same file, the place you teleport your DOM element to can be **anywhere** in your React code. So you could teleport it to a completely different sub component, element, or parent anywhere in the DOM. It's pretty powerful, and useful - so use it wisely.

Let's look back at our `App.js` HTML:
```html   
    <!-- .... -->
    <button onClick={() => setIsModalOpen(!isModalOpen)}>
        Click to Open Modal
    </button>
    <Modal modalState={isModalOpen} onClickEvent={() => setIsModalOpen(!isModalOpen)}>
        This is Modal Content!
    </Modal>
</header>
<div id="modal-container"></div>
```

Now, even though `Modal` sits in our header, it will appear in `#modal-container` whenever we open the modal using the button:
![How Portals work in React](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/9iyifjdyohu7hjimnjbh.png)


## Conclusion

Portals are a pretty powerful tool in React. They are a useful way to solve the main issue with component based systems - transporting certain elements above all the rest. As such, I hope you've enjoyed this guide to React portals. If you are learning React, I'd suggest mastering Javascript first - which you can do with my full [Javascript Handbook](https://fjolt.com/series/learn-javascript).

Have a great day.