useCheckpoints
The useCheckpoints
hook is used to get a reference to a Checkpoints
object from within a Provider
component context.
useCheckpoints(id?: string): Checkpoints | undefined
Type | Description | |
---|---|---|
id? | string | An optional |
returns | Checkpoints | undefined | A reference to the Checkpoints object (or `undefined` if not within a Provider context, or if the requested Checkpoints object does not exist) |
A Provider
component is used to wrap part of an application in a context. It can contain a default Checkpoints
object (or a set of Checkpoints
objects named by Id
) that can be easily accessed without having to be passed down as props through every component.
The useCheckpoints
hook lets you either get a reference to the default Checkpoints
object (when called without an parameter), or one of the Checkpoints
objects that are named by Id
(when called with an Id
parameter).
Examples
This example creates a Provider context into which a default Checkpoint object is provided. A component within it then uses the useCheckpoints
hook to get a reference to the Checkpoints
object again, without the need to have it passed as a prop.
const App = ({checkpoints}) => (
<Provider checkpoints={checkpoints}>
<Pane />
</Provider>
);
const Pane = () => (
<span>{useCheckpoints().getListenerStats().checkpointIds}</span>
);
const checkpoints = createCheckpoints(createStore());
const app = document.createElement('div');
ReactDOM.render(<App checkpoints={checkpoints} />, app);
console.log(app.innerHTML);
// -> '<span>0</span>'
This example creates a Provider context into which a Checkpoints
object is provided, named by Id
. A component within it then uses the useCheckpoints
hook with that Id
to get a reference to the Checkpoints
object again, without the need to have it passed as a prop.
const App = ({checkpoints}) => (
<Provider checkpointsById={{petStore: checkpoints}}>
<Pane />
</Provider>
);
const Pane = () => (
<span>
{useCheckpoints('petStore').getListenerStats().checkpointIds}
</span>
);
const checkpoints = createCheckpoints(createStore());
const app = document.createElement('div');
ReactDOM.render(<App checkpoints={checkpoints} />, app);
console.log(app.innerHTML);
// -> '<span>0</span>'