React LoadIt

Simple, tiny React component lazy-loader. Splits your React app at defined points at the component-level, so there's no unnecessary code delivered.

Published from a part of a private project I wrote. Thought I'd share it with you.

PS - If you're looking for a full-on, feature-rich version, I would use react-loadable.

Install

yarn add react-loadit

• The build is CommonJS and works also with import/export using Babel.

Usage

Example of conditionally loading inside a modal.

<div>
  {this.state.clicked && (
    <Modal>
      <LoadIt {...otherProps} load={() => import('./OtherComponent')} />
    </Modal>
  )}
</div>

Webpack ideal setup

// webpack.config.js

// ...

// for dynamic imports this takes care of
// grouping loaded chunks, to load only *once*
// NOTE: Webpack 4 might negate the need for this
new CommonsChunkPlugin({
  minChunks: 2,
  children: true,
  deepChildren: true,
  async: true,
}),

// ...

Demo

Run yarn && yarn start from a directory inside ./examples.

Dependencies: You'll need to install create-react-app globally.

API

load

func|arr, required

• Default export: () => import(...)
• Named (single) export: [() => import('./Exported'), 'SomeExport']
  • @todo - multiple named exports?

A component to dynamically load.

Default export

<LoadIt load={() => import('./LoadMe')} />

Named export

<LoadIt load={[ () => import('./LoadMe'), 'LoadThisExport' ]} />

loadingComponent

func: (obj) => element

const renderLoading = ({ loadError, loadTimeout, pastDelay }) => {
  if (loadError) {
    return <div>Load error</div>;
  } else if (pastDelay && !loadTimeout) {
    return <LoadingSkeleton />;
  } else if (loadTimeout) {
    return <div>Taking awhile...</div>;
  }
  return null;
};

Return an optional component to show while loading. Passes an object to be used to create a more complex loading component (e.g. load fails).

• loadError (bool) - true if load failed.
• loadTimeout (bool) - true if timeout prop is set and timeout length has past.
• pastDelay (bool) - true if delay is set and delay time has past.

delay

int (default: 250)

<LoadIt delay={200} loadingComponent={...} ... />

Good to use for components that are taking awhile (> ~200ms) to load (possibly on a slow connection, or the component is large in size). Use with loadingComponent.

The basic idea is to show nothing until this delay has past, then showing a spinner or message to the effect of "loading...". Research has shown the user will perceive the app as being faster if no spinner is shown before 200ms. Makes sense.

timeout

int

<LoadIt timeout={10000} loadingComponent={...} ... />

Good to use for components that are taking their time 🐢 to load (possibly on a slow connection, or the component is large in size). Use with loadingComponent.

shouldLoad

bool

<LoadIt shouldLoad={this.state.data.length && true} ... />

This is optional and simply an opportunity to avoid nesting the component inside if/else logic inside of render(). This will load the core <LoadIt />, but not dynamically load the desired file, or loading views, until the logic returns true.

This pattern can be helpful in a situation where you want to show a wrapping component.

Running tests

Pull the repo and run yarn && yarn test.