Redux loader example

ReduxLoader.js

class IsLoading extends React.Component {
    constructor(props) {
        super(props)
        this.state = { isLoading: false }
    }
    async componentDidCatch(err) {
        if (err instanceof Promise) {
            this.setState({ isLoading: true }) 
            await err
            this.setState({ isLoading: false })
        } else {
            throw err
        }
    }
    render() {
         return this.props.children(this.state.isLoading)
    }
}

export const Loader = (props) => (
  <IsLoading>
    {(loading: boolean) => (loading  ? 'Loading...' : props.children)}
  </IsLoading>
)