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mkg0/promise-effects
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Fully typed promise effects to play with async handlers in a pleasent way.
| Effect | Desc |
|---|---|
| retryPromise | Converts a promise creator to repetitive |
| wait | Creates a promise to resolve for the given time long. |
| observePromise | Creates observable promises from the given promise |
| timeout | Timeout example |
| Polling | ⏱ Polling example |
| Latest | ⏱ |
| CancelablePromise | ⏱ |
Install package
npm install promise-effects
Import module
import{retryPromise}from'promise-effects'// orimportretryPromisefrom'promise-effects/retryPromise'
It's a high-order function that gives the capabilify of retry to a function that creates promise.
constrepetitiveFetch=retryPromise(fetch,{retry:3,onReconnecting:({ attemptNumber})=>console.log(`Fetching has failed(${attemptNumber})... Retrying...`),})repetitiveFetch('https://www.mocky.io/v2/5185415ba171ea3a00704eed').then(resp=>resp.json()).then(console.log).catch(()=>console.log('Failed!'))// > Fetching has failed(1)... Retrying...// > Fetching has failed(2)... Retrying...// > Fetching has failed(3)... Retrying...// > Failed!
| Option Name | Type |
|---|---|
| onReconnecting | fn:({attemptNumber: number, remainingTries: number, error: Error}) |
| delay | number |
| delay | { delay: number, factor: number, max?: number, min?: number } |
| delay | `fn: ({attemptNumber: number, remainingTries: number, error: Error}) => number |
| shouldRetry | `fn: ({attemptNumber: number, remainingTries: number, error: Error}) => booleaan |
| retry | number |
It wraps promises to observe the status. You can get if the promisefulfilled,rejected orpending. It's beneficial on test purposes.
constobserved=observePromise(fetch('http://google.com'))console.log(observed.isPending())// > trueconsole.log(observed.isRejected())// > falseconsole.log(observed.isFulfilled())// > falseconsole.log(observed.status)// > 'PENDING'observed.then(result=>{console.log(observed.status)// > 'RESOLVED'console.log(observed.isFulfilled())// > true}).catch(()=>{console.log(observed.status)// > 'REJECTED'console.log(observed.isRejected())// > true})
Creates a promise to resolve for the given time long.
constprintMessage=(count=0)=>Promise.resolve().then(()=>console.log(`You will see this message every second(${count})`)).then(()=>wait(1000).then(()=>printMessage(count+1)))printMessage()// > You will see this message every second(0)// > You will see this message every second(1)// > You will see this message every second(2)// > You will see this message every second(3)// > ...
You don't need an exclusive timeout function for timeout. Usewait withES Promise.race instead.
// fail in 1 secPromise.race([fetch('https://www.mocky.io/v2/5185415ba171ea3a00704eed?mocky-delay=1200ms').then(res=>resp.json()),wait(1000).then(()=>Promise.reject('Timeout!'))])// > Uncaught (in promise) Timeout!
// will mock response if the first request doesn't resolve in 1 secconstresult=awaitPromise.race([fetch('https://www.mocky.io/v2/5185415ba171ea3a00704eed?mocky-delay=1200ms').then(res=>resp.json()),wait(1000).then(()=>({hello:'mock'}))])console.log(result)// > { hello: 'mock' }
All notable changes to this project will be documented in thechangelog file.
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Promise effects like retry, timeout, observation over promises for advanced use cases or test purposes.
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