JS client for Pusher Feeds
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README.md

Feeds Client JavaScript reference

The JavaScript client for Pusher Feeds. If you aren't already here, you can find the source on Github.

For more information on the Feeds service, see here. For full documentation, see here

Installation

yarn:

$ yarn add @pusher/feeds

In a script tag:

<script src="https://unpkg.com/@pusher/feeds"></script>

Instantiate a Feeds object

The constructor Feeds takes a single options object with the following properties.

  • instanceLocator: [required] get this from your dashboard

  • authEndpiont: [optional] the endpoint to use to request tokens for access to private feeds

  • authData: [optional] data to pass to the auth endpoint along with token requests

  • logLevel: [optional] a number between 1 and 5, corresponding to VERBOSE, DEBUG, INFO, WARNING, and ERROR respectively. 1 logs everything, 5 only logs errors etc.

  • logger: [optional] a cutom logger implementation, must conform to the following interface

interface Logger {
    verbose(message: string, error?: Error);
    debug(message: string, error?: Error);
    info(message: string, error?: Error);
    warn(message: string, error?: Error);
    error(message: string, error?: Error);
}

Example

const feeds = new Feeds({ instanceLocator: your_instance_locator });

Get a reference to a feed

Given the feeds object above, feeds.feed Returns a reference to a particular feed, from which subscriptions and history queries can then be made. Takes a feedId.

Example

const yourFeed = feeds.feed(your_feed_id);

Subscribe to a feed

Given a feed object such as yourFeed above, use yourFeed.subscribe to receive new items published to yourFeed. A subscription can be resumed from some previously seen item by providing a lastItemId, or can be initiated with a fixed number of previously seen items by providing the previousItems option. Private feeds require "READ" permission. Takes a single options object with the following properties.

  • onItem: [required] callback to handle items, takes each item as a parameter

  • lastItemId: [optional] retrieve every item published after lastItemId, and then live items as they are published

  • previousItems: [optional] if this parameter is provided, then the most recent previousItems items will be retrieved, followed by live items as they are published (lastItemId takes precedence if both are provided)

  • onOpen: [optional] callback to fire when the subscription is open, takes an object containing next_cursor and remaining as a parameter

  • onEnd: [optional] callback to fire when the subscription ends normally

  • onError: [optional] callback to fire when the subscription is closed with error

Returns a subscription object with an unsubscribe method.

Items are passed to the onItem callback with the following format

{
  id: item_id, // this corresponds to the published item_id
  created: timestamp,
  data: item_data
}

Example

const subscription = feed.subscribe({
  previousItems: 10,
  onOpen: ({ next_cursor, remaining }) => {
    // Keep track of next_cursor and remaining if you might want to paginate
    // back through previous items later on [optional]
  },
  onItem: item => {
    // Update the DOM with the item
  },
  onError: error => {
    console.error(`Error with subscription: ${error}`)
  },
});

// Unsubscribe after 5 seconds
setTimeout(subscription.unsubscribe, 5000);

Pagination

Given a feed object such as yourFeed above, use yourFeed.paginate to query a feed for pages of previously published items. Items are returned in descending order of item ID. Private feeds require "READ" permission. Takes a single (optional) options object with the following properties.

  • cursor: [optional] the ID of the first item in the page – if not provided, retrieves the most recently published items

  • limit: [optional] limit the number of items to retrieve

Returns a promise resolving with a single object of the following format.

{
  items: [
    ...
    {
      id: item_id,
      created: timestamp,
      data: item_data
    }
    ...
  ],
  next_cursor: next_cursor,
  remaining: remaining
}

next_cursor should be used as the cursor parameter to get the next page of results. It will be null if there are no more results. remaining is a count of the number of unseen items further back in the history of the feed.

Example

// Get a page containing the last 25 items (but don’t subscribe)
yourFeed.paginate({ limit: 25 }).then(({ items }) => {
  // Update the DOM with the items
});

List feeds for an instance

Given a feeds object feeds, feeds.list lists non-empty feeds. This method requires "READ" permission on the path "feeds", see the auth docs. Takes a single options object with the following properties.

  • prefix: [optional] only return those feeds that start with this string

  • limit: [optional] return at most this many matches

Subscribe to the Firehose

Given a feeds object feeds, feeds.firehose subscribes to the firehose for this instance to see all events and subscriptions on a single subscription. This method requires "READ" permission on the path "firehose/items" – see auth docs. Takes a single options object with the following properties

  • onPublish: callback to fire when a Publish event is received

  • onSubscribe: callback to fire when a Subscribe event is received

  • onUnsubscribe: callback to fire when an Unsubscribe event is received

  • onOpen: [optional] callback to fire when the subscription is open

  • onEnd: [optional] callback to fire when the subscription ends normally

  • onError: [optional] callback to fire when the subscription is closed with error

At least one of onPublish, onSubscribe, and onUnsubscribe must be provided.