Middlewares for the wretch library
npm install wretch-middlewares``sh`
npm i wretch-middlewares
`html`
| Dedupe | Retry | Throttling cache | Delay |
|-----|-----|-----|-----|
Prevents having multiple identical requests on the fly at the same time.
#### Options
- skip : (url, opts) => boolean
If skip returns true, then the dedupe check is skipped.
- key : (url, opts) => string
Returns a key that is used to identify the request.
- resolver : (response: Response) => Response
This function is called when resolving the fetch response from duplicate calls.
By default it clones the response to allow reading the body from multiple sources.
#### Usage
`js
import wretch from 'wretch'
import { dedupe } from 'wretch-middlewares'
wretch().middlewares([
dedupe({
/ Options - defaults below /
skip: (url, opts) => opts.skipDedupe || opts.method !== 'GET',
key: (url, opts) => opts.method + '@' + url,
resolver: response => response.clone()
})
])./ ... /
`
Retries a request multiple times in case of an error (or until a custom condition is true).
#### Options
- delayTimer : milliseconds
The timer between each attempt.
- delayRamp : (delay, nbOfAttempts) => milliseconds
The custom function that is used to calculate the actual delay based on the the timer & the number of attemps.
- maxAttempts : number
The maximum number of retries before resolving the promise with the last error. Specifying 0 means infinite retries.
- until : (fetchResponse, error) => boolean | Promise
The request will be retried until that condition is satisfied.
- onRetry : ({ response, error, url, options }) => { url?, options? } || Promise<{url?, options?}>
Callback that will get executed before retrying the request. If this function returns an object having url and/or options properties, they will override existing values in the retried request. If it returns a Promise, it will be awaited before retrying the request.
- retryOnNetworkError : boolean
If true, will retry the request if a network error was thrown. Will also provide an 'error' argument to the onRetry and until methods.
- resolver : (response: Response) => Response
This function is called when resolving the fetch response from duplicate calls.
By default it clones the response to allow reading the body from multiple sources.
#### Usage
`js
import wretch from 'wretch'
import { retry } from 'wretch-middlewares'
wretch().middlewares([
retry({
/ Options - defaults below /
delayTimer: 500,
delayRamp: (delay, nbOfAttempts) => delay * nbOfAttempts,
maxAttempts: 10,
until: (response, error) => response && response.ok,
onRetry: null,
retryOnNetworkError: false,
resolver: response => response.clone()
})
])./ ... /
// You can also return a Promise, which is useful if you want to inspect the body:
wretch().middlewares([
retry({
until: response =>
response.json().then(body =>
body.field === 'something'
)
})
])
`
A throttling cache which stores and serves server responses for a certain amount of time.
#### Options
- throttle : milliseconds
The response will be stored for this amount of time before being deleted from the cache.
- skip : (url, opts) => boolean
If skip returns true, then the dedupe check is skipped.
- key : (url, opts) => string
Returns a key that is used to identify the request.
- clear (url, opts) => boolean
Clears the cache if true.
- invalidate (url, opts) => string | RegExp | Array
Removes url(s) matching the string or RegExp from the cache. Can use an array to invalidate multiple values.
- condition response => boolean
If false then the response will not be added to the cache.
- flagResponseOnCacheHit string
If set, a Response returned from the cache whill be flagged with a property name equal to this option.
#### Usage
`js
import wretch from 'wretch'
import { throttlingCache } from 'wretch-middlewares'
wretch().middlewares([
throttlingCache({
/ Options - defaults below /
throttle: 1000,
skip: (url, opts) => opts.skipCache || opts.method !== 'GET',
key: (url, opts) => opts.method + '@' + url,
clear: (url, opts) => false,
invalidate: (url, opts) => null,
condition: response => response.ok,
flagResponseOnCacheHit: '__cached'
})
])./ ... /
`
Delays the request by a specific amount of time.
#### Options
- time : milliseconds
The request will be delayed by that amount of time.
#### Usage
`js
import wretch from 'wretch'
import { delay } from 'wretch-middlewares'
wretch().middlewares([
delay(1000)
])./ ... /
``