#fetch-link

Extension of fetch to recursively fetch resources using the Link header

API

next, prev, first, last

Methods that will fetch the given linked resource if specified in the 'Link' header. Each function accepts two parameters (res, options) and returns a promise for a Response

• res Either a Response instance or the value of the Link header extracted from a Response object
• options object to pass in to the fetch request for th elinked resource

all(url, options)

Recursively fetches all linked resources, beginning with the given url. Returns a promise for an array of Response instances

• url The url to fetch
• options Object to configure requests and recursive behaviour. Accepts the following properties (all optional)
  • fetch An object that will be passed as the optiosn to every fetch request sent. Can also be afunction, expecting url as the first parameter, and returning an optiosn object, so that each fetch can be configured independently e.g. send a different eTag with each fetch
  • direction 'next' or 'prev', indicating which direction to follow links in (default is to follow both 'next' and 'prev')
  • limit maximum number of links to follow. Note that the behaviour when specifying limit and not specifying direction is not guaranteed to produce the same results every time because e.g. a single slow response in the 'next' direction can result in requests being weighted towards the 'prev' direction
  • failGracefully By default a single failed response will cause all() to reject with the error thrown. If failGracefully is true then it will continue to follow links in the opposite direction to the one which has errored and eventually resolve with a promise for an array of responses with the error returned in the first/last place. This only applies to javascript errors thrown by fetch; http errors (503 etc) count as succesful responses and if the response specifies a Link header then it will be followed as normal.

setFetchImplementation(func)

Use a custom implementation of fetch