README.md
# promise-reject-status-above [![Build Status](https://travis-ci.org/songkick/promise-reject-status-above.svg)](https://travis-ci.org/songkick/promise-promise-reject-status-above) [![Code Climate](https://codeclimate.com/github/songkick/promise-reject-status-above/badges/gpa.svg)](https://codeclimate.com/github/songkick/promise-reject-status-above) [![Test Coverage](https://codeclimate.com/github/songkick/promise-reject-status-above/badges/coverage.svg)](https://codeclimate.com/github/songkick/promise-reject-status-above/coverage)
Rejects a promise returned by `fetch()` if status above threshold
```js
var rejectStatusAbove = require('@songkick/promise-reject-status-above');
var rejectAbove400 = rejectStatusAbove({status: 400});
function fetch200(){
return fetch('/path/to/a/http-200-ok');
}
function fetch400(){
return fetch('/path/to/a/http-400-bad-request');
}
rejectAbove400(fetch200)()
.then(function(response){
// the initial fetch response
}).catch(function(err){
// probably won't happen here, unless /200 doesn't return a HTTP - 200
});
rejectAbove400(fetch400)()
.then(function(response){
// should not happen here
}).catch(function(err){
// err instanceof rejectStatusAbove.StatusAboveError === true
// err === {
// message: 'Response status above accepted status',
// settings: {
// status: 400,
// },
// fn: fetch400,
// response: window.Response // the original fetch Response
// }
});
```
## Options
`status`: positive (>= 0) number. The returned promise will be rejected if the
response's status is equal or above this number.
## Composition
As `promise-reject-status-above` input and output is a function returning a promise, you can compose them easily with other simial helpers ([see below](#see-also)).
In the example below, our `/data` API is a bit janky and might return HTTP 500 errors. We'll retry them twice before giving up.
```js
var promiseRetry = require('@songkick/promise-retry');
var rejectStatusAbove = require('@songkick/promise-reject-status-above');
var retryTwice = promiseRetry({ retries: 2 });
var rejectAbove500 = rejectStatusAbove({status: 500});
function fetchData() {
// this call might return 500 sometimes
return fetch('/data');
}
retryTwice(rejectAbove500(fetchData))().then(function(response){
// yay !
}).catch(function(err){
// we retried the call twice but always got 500s :(
});
```
# See also
`promise-reject-status-above` composes really well with the following promise helper:
* [`promise-retry`](https://github.com/songkick/promise-retry)
* [`promise-timeout`](https://github.com/songkick/promise-timeout)