react-loadable-visibility

A wrapper around react-loadable and @loadable/component, only loading imports that are visible on the page.

Example using react-loadable

import LoadableVisibility from "react-loadable-visibility/react-loadable";
import Loading from "./my-loading-component";

const LoadableComponent = LoadableVisibility({
  loader: () => import("./my-component"),
  loading: Loading
});

export default function App() {
  return <LoadableComponent />;
}

Example using @loadable/component

import loadableVisibility from "react-loadable-visibility/loadable-components";
import Loading from "./my-loading-component";

const LoadableComponent = loadableVisibility(() => import("./my-component"), {
  fallback: <Loading />
});

export default function App() {
  return <LoadableComponent />;
}

Options

The API is exactly the same as the original library. Please refer to their documentation:

• react-loadable documentation
• @loadable/component documentation

Note that you'll need to have react-loadable or @loadable/component in your package.json.

How does this work?

It's in essence a wrapper around loadable libraries with hooks into an IntersectionObserver to inform us of when a given element is in the viewport.

Therefore, it will only function in browsers that have the IntersectionObserver API.

A polyfill for IntersectionObserver is available however I am skeptical of its performance but have not tested it fully to offer a recommendation here. If you have any comments about this, feel free to open a PR and adjust this README!

If you choose the use the polyfill, you can load it via a polyfill.io script - <script crossorigin="anonymous" src="https://polyfill.io/v3/polyfill.min.js?features=IntersectionObserver%2CIntersectionObserverEntry"></script>

Otherwise if the IntersectionObserver API is not available, we will revert back to just using react-loadable or @loadable/component itself.

Why do I want this?

react-loadable and @loadable/component are fantastic higher level components to load additional modules once they are mounted on your page. It's great for keeping your bundle size small and pulling in a larger payload when the required components are part of your tree.

However it will not account for the content that's currently visible on your page, and only load what's actually visible to the end user. If you have a long page and are loading the entire content of that page for the user, even though they may only be able to see the content above the fold, it can be wasteful and especially detrimental in a mobile context.

react-loadable-visibility is positioned to solve these issues by leveraging the existing awesome API of loadable libraries with an extension to only trigger the loading of additional content once that component comes into view.

Contributors

We'd like to thank the following people for their contributions:

• Tasveer Singh
• Bergé Greg

Have a look at the GitHub contributors page for a full list of all contributors.

License

react-loadable-visibility may be redistributed according to the BSD 3-Clause License.

Copyright 2019, Stratiform Limited.