React Watcher

Simple helper to watch your React components prop changes.

Requires React to render components.

Note: Using this library for watching prop changes is highly discouraged. It is however the only way of watching prop changes when using external libraries or very complex component trees prop configurations.

Install

npm install react-watcher

Examples

Quickstart

Wrap a component to access watch (and unwatch) binding functions.

import connect from 'react-watcher';

class UserDetail extends React.PureComponent {
  render() {
    const { id } = this.props;

    return (<div>{id}</div>);
  }
  componentWillMount() {
    const { watch } = this.props;

    watch('id', (newId) => {
      // New ID assigned, you can use this to dispatch a user fetch action or
      // any other Redux action dispatch or function call.
    });
  }
}

export default connect(UserDetail);

Note: The prop to watch can be any value accepted by Lodash _.get function. Examples: 'params.id', 'users[0].id', ['users', 0, 'id'].

API

connect

Connect the React component to get the watch and unwatch props for binding the prop change events.

Arguments

• Component (required) – The React component to connect to.

Exposed props

• watch(propPath, callback) – Binds the prop change to the given callback.
• unwatch(propPath) – Removes the binding. Note: unwatch doesn't need to be called on component unmount. Bindings will be freed automatically.

Common pitfalls

Using this library for watching prop changes that you change directly is highly discouraged. Instead, call the prop change callback when the change is performed.

/* Bad */
class UsersList extends React.Component {
  render() {
    const { activeFilter, users } = this.props;

    return (/* ... */);
  }
  toggleActive(event) {
    dispatch(toggleActiveAction());
  }
  componentWillMount() {
    this.props.watch('activeFilter', (activeFilter) => {
      alert('Active filter has changed!');
    })
  }
}

export default connect(UsersList);

/* Good */
class UsersList extends React.Component {
  render() {
    const { activeFilter, users } = this.props;

    return (/* ... */);
  }
  toggleActive(event) {
    dispatch(toggleActiveAction());
    alert('Active filter has changed!');
  }
}

Authors

Sebastián Borrazás

• sborrazas.com

License

MIT