README
react-memoized context
Avoid unnecessary re-renders when consuming partially a React Context.
- < 1kb GZIP 🔬
- Tree-shakable 🌴
Motivation
When a component has simple props, using PureComponent
/Memo()
is a possible solution to avoid extra re-renders from props coming from Context. However, components with complex props might perform worse when using PureComponent
. It's in that moment that react-memoized-context
rocks. It works like PureComponent
/Memo()
but it only performs the shallow comparison to props coming from Context.
See a Working Demo showing the benefits of react-memoized-context
.
Installing
npm install react-memoized-context --save
Using
A. HOC
import { withMemoizedContext } from 'react-memoized-context';
const FootNote = ({ context, ...otherProps }) => {
/*... do stuff with context.name ...*/
}
// Only re-renders FootNote when UserContext.name changes.
const FootNoteContexted = withMemoizedContext(UserContext)(FootNote, ['name']);
B. Component renderProp
import { MemoizedContext } from 'react-memoized-context';
// Only re-renders FootNote when UserContext.name changes.
<MemoizedContext context={ UserContext } memoKeys={ ['name'] }>
({ name }) => <FootNote author={ name } />
</MemoizedContext>
C. Hook?
Well... the way React hooks work, it's impossible to directly subscribe to a part of the context value without re-rendering. See React issue #14110
function FootNote() {
const { name } = useContext(UserContext);
// FootNote re-renders when UserContext value changes, even if name is the same.
<FootNote author={ name } />
}
Workaround
Use an extra hook useMemo
as a wall between the Context part and the rest of the Component children. See React issue #15156.
function FootNote() {
const { name } = useContext(UserContext);
// Only re-renders FootNote when name is updated.
return useMemo(() => (
<FootNote author={ name } />
), [name])
}
See full Documentation with Demo.
Contributing
- Development:
yarn docz:dev
- Testing:
yarn test
Feel free to open an issue or PR.