cancelable-fetch

Makes a fetch cancelable.

Usage

cancelable-fetch wraps an existing fetch and adds a cancel method. Only the headers will be fetched if the response body of fetch supports cancel. The request can't be canceled before, because the fetch interface doesn't provide a method for it. In any case, if cancel was called, an user cancelation error will be thrown.

The Promise standard doesn't support cancel. Therefore always use the return value of cancelable-fetch, because cancel will not be forwarded in the Promise chain!

Example

In this example doRequest takes care that only the latest request will respond.

var cancelableFetch = require('cancelable-fetch')

var request = null

function doRequest () {
  // check if there is a running request
  if (request) {
    // cancel that request
    request.cancel()
  }

  // wrap the new request with cancelableFetch
  request = cancelableFetch(fetch(url)).then(function (res) {
    // remove running request
    request = null

    // forward response
    return res
  })

  return request
}