getChannelMessages(channelName: string): BaseMessage<unknown>[] | undefined¶
The getChannelMessages is a method that allows to retrieve an array of past events from a given channel.
Accessing past channel messages is important in many situations, for example:
- Synchronizing web components that are added to the page after initial load.
- Restoring the state of web components when users navigate back.
- Implementing undo/redo capabilities.
NOTE: It is a good practice to ensure all previous events get handled regardless of when a webcomponent gets loaded into the page.
Input parameters¶
channelName¶
channelName is a mandatory parameter of the string type which represents the name of the event.
Returned value¶
A returned value has a type of BaseMessage<unknown>[]. If past events in a given channel do not exist, the returned value is undefined.
Example¶
In this example we make a messageStorageSystemApi call to retrieve an array of past events.
useStorefront((storefront) => {
const messageStorageApi = storefront.getApiSync('messageStorageSystemApi');
const pastStockChangedEvents = messageStorageApi.getChannelMessages('product.stockChanged');
if (pastStockChangedEvents.length > 0) {
pastStockChangedEvents.forEach(({ body: eventBody }) => {
console.log('perform action on every past event');
});
}
});