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2.2.2 • Public • Published

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Unfortunately React.PureComponent is not embracing Immutable.js to it full potential. While Immutable.js provides hash value, witch allows for fast comparison of two different instances React.PureComonent is only comparing addresses of those instances.

The ImmutablePureComponent uses is to compare values and extends component functionality by introducing:

  • updateOnProps
  • updateOnStates

With those properties you can specify list of props or states that will be checked for changes. If value is undefined (default) then all props and state will be checked, otherwise array of keys or paths is expected. The path is an Array of keys like in the example below. Path values are working for any mix of supported collection as long as given key exists, otherwise checked value is undefined. Immutable.Collection, plain Objects, Arrays, es6 Map and any collection providing get and has functionality are all supported.

type UpdateOn<T> = Array<$Keys<T> | any[]>;

export class ImmutablePureComponent<
  State = void,
> extends React$Component<Props, State> {

  updateOnProps: UpdateOn<Props>;
  updateOnStates: UpdateOn<State>;

export default ImmutablePureComponent;


With React 16.6.0 we ware introduced to React.memo a React.PureComponent equivalent for functional components. And the same story goes here, unfortunately React.memo is not fully embracing Immutable potential. That is where immutableMemo steps in. This is wrapper over React.memo with custom comparison function. immutableMemo accepts component as first argument and optionally array of property keys or paths the same way as updateOnProps is working for ImmutablePureComponent.

export function immutableMemo<Props>(
  component: React$ComponentType<Props>,
  updateOnProps?: UpdateOn<Props>,
): React$ComponentType<Props>;


In this example component will update when value of me is change and will ignore changes of data, check or any other property. Component will also update on change of first element of buzz or change to type and will ignore changes to the rest of the state.

class Example extends ImmutablePureComponent {
  state = {
    fis: { 
      buzz: Immutable.List([10, 11])
      ignore: 'this',
    type: undefined,
  updateOnStates = [
    ['fis', 'buzz', 0],
  updateOnProps = [
    ['data', 'check', 'me'],
  render() {...}
let data = Immutable.Map({ check: new Map([['me', true]]) }) 
ReactDOM.render(<Example data={data} onChange={() => {}}, root);

To check what its all about checkout the interactive example :D

Interactive example.


npm i react-immutable-pure-component

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