react-unplug

Promise-wrapper to manage the state of react components. Inspired by this article from React blog.

Installation

# npm
npm install react-unplug

# yarn
yarn add react-unplug

Overview

For React components, that use fetch to update the state, unmounting can lead to the following issue:

setState(…): Can only update a mounted or mounting component. This usually means you called setState() on an unmounted component. This is a no-op

The correct way to fix this issue, according to the article, is to cancel any callbacks in componentWillUnmount, prior to unmounting.

React-unplug uses the idea of socket–plug–unplug to prevent setting the state of a react component once it is told to do so.

Usage

Let's say you have a react component that fetches a resource and once it's successfully done, fetches related resources. Usually you want to do that in componentDidMount.

componentDidMount() {
  fetchResource(this.props.url)
    .then(item => {
      this.setState({item})
      fetchRelatedResources(item)
        .then(relatedItems => {
          this.setState({relatedItems});
        })
        .catch(error => { /* handle */ })
    })
    .catch(error => { /* handle */ });
}

If a user's actions cause the component unmounting or rerendering with different props, there is a chance, that setState will try to set state of an unmounted component. In this case react will give us very nice warning that we might want to get rid off.

To do so, let's plug our promises to the socket. This gives us a way to unplug them when we need, preventing a call to setState.

import unplug from 'react-unplug';

Let's update our component with wired promises:

socket = unplug.socket();

componentDidMount() {
  this.socket.plug(wire => wire(
    fetchResource(this.props.url),
    item => {
      this.setState({item});
      wire(
        fetchRelatedResources(item),
        this.setState({relatedItems}),
        error => { /* handle */ }
      )
    },
    error => { /* handle */ }
  ));
}

componentWillUnmount() {
  this.socket.unplug();
}

Done! Wired promises' onFulfilled, onRejected handlers won't be called once the socket is unplugged.

Running the tests

# with npm
npm test

# with yarn
yarn test

Contributing

Please read CONTRIBUTING.md for details on our code of conduct, and the process for submitting pull requests to us.

Versioning

SemVer is used for versioning. For the versions available, see the tags on this repository.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• @istarkov for original makeCancelable implementation here