Promise with state
What is this?
A library to use queryable promises or make native promise A+ queryable.
Why?
According to Promises/A+ standard definition, a Promise is a "thenable" object, which sets itself into 3 different states: PENDING, FULFILLED, or REJECTED. However, there is no way to ask a promise which state it is only know it has fulfilled or rejected. With this library you can create queryable promise or make native promise queryable.
How to use it?
First you need to import it in your project.
The require way
let { QueryablePromise } = require("promise-with-state");The import way
import { QueryablePromise } from "promise-with-state";Then you can instantiate QueryablePromise to create Promises that are queryable for its state.
- in the case it resolves
import { QueryablePromise } from "promise-with-state";
const queryableWithResolution = new QueryablePromise((resolve, reject) => {
// YOUR OWN CODE AND STUFF
resolve()
})
console.log(queryableWithResolution.state)
// PENDING
console.log(queryableWithResolution.isPending())
// true
console.log(queryableWithResolution.isFulfilled())
// false
console.log(queryableWithResolution.isRejected())
// false
queryableWithResolution
.then(() => {
console.log(queryableWithResolution.state)
// FULFILLED
console.log(queryableWithResolution.isPending())
// false
console.log(queryableWithResolution.isFulfilled())
// true
})
.catch()- in the case it rejects
import { QueryablePromise } from "promise-with-state";
const queryableWithRejection = new QueryablePromise((resolve, reject) => {
// YOUR OWN CODE AND STUFF
reject()
})
console.log(queryableWithRejection.state)
// PENDING
console.log(queryableWithRejection.isPending())
// true
console.log(queryableWithRejection.isFulfilled())
// false
console.log(queryableWithRejection.isRejected())
// false
queryableWithRejection
.then() // promises always should has thenable
.catch(() => {
console.log(queryableWithRejection.state)
// REJECTED
console.log(queryableWithRejection.isPending())
// false
console.log(queryableWithRejection.isRejected())
// true
})The states for queryable promises are grouped in a constant called QueryablePromiseState
import { QueryablePromise, QueryablePromiseState } from "promise-with-state";
const queryablePromise = new QueryablePromise((resolve, reject) => {
// YOUR OWN CODE AND STUFF
})
console.log(queryablePromise.state)
// PENDING
console.log(queryablePromise.isPending())
// true
console.log(queryablePromise.state === QueryablePromiseState.PENDING)
// true
console.log(queryablePromise.isFulfilled())
// false
console.log(queryablePromise.isRejected())
// falseNative thenables can be transformed into queryable promises with makeQueryablePromise.
import { makeQueryablePromise, QueryablePromiseState } from "promise-with-state";
const processTextPromise = new Promise((resolve, reject) => {
// YOUR OWN CODE AND STUFF
if (condition) {
resolve()
} else {
reject()
}
})
const queryableTextPromise = makeQueryablePromise(processTextPromise)
console.log(queryableTextPromise.state)
// PENDING
console.log(queryableTextPromise.isPending())
// true
console.log(queryableTextPromise.isFulfilled())
// false
console.log(queryableTextPromise.isRejected())
// false
processTextPromise
// if resolves
.then(() => {
console.log(processTextPromise.state)
// FULFILLED
console.log(processTextPromise.isPending())
// false
console.log(processTextPromise.isFulfilled())
// true
})
// if rejects
.catch(() => {
console.log(processTextPromise.state)
// REJECTED
console.log(processTextPromise.isPending())
// false
console.log(processTextPromise.isRejected())
// true
})
.finally(() => {
console.log(processTextPromise.isPending())
// false
})Powered by https://xisco.dev
Additional JSDOC info
JSDOC
Table of Contents
makeQueryablePromise
Transform any promise to queryable promise.
Parameters
-
thenablePromise the promise to be transformed
Returns any a promise enhanced with state query methods
isPending
retrieves true if queried state is actual queryable promise state.
Returns boolean true when queryable promise state is PENDING
isFulfilled
retrieves true if queried state is actual queryable promise state.
Returns boolean true when queryable promise state is FULFILLED
isRejected
retrieves true if queried state is actual queryable promise state.
Returns boolean true when queryable promise state is REJECTED
QueryablePromise
Extends Promise
Parameters
-
executorCallableFunction function which contains fulfill and reject resolvers for Promise
state
Getter for queryable promise state.
Type: string
Returns QueryablePromiseState contains current promise state
isPending
retrieves true if queried state is actual queryable promise state.
Returns boolean true when queryable promise state is PENDING
isFulfilled
retrieves true if queried state is actual queryable promise state.
Returns boolean true when queryable promise state is FULFILLED
isRejected
retrieves true if queried state is actual queryable promise state.
Returns boolean true when queryable promise state is REJECTED
QueryablePromiseState
Contains queryable promise states
Type: object
PENDING
Promise state PENDING for queryable
Type: QueryablePromiseState
FULFILLED
Promise state FULFILLED for queryable
Type: QueryablePromiseState
REJECTED
Promise state REJECTED for queryable
Type: QueryablePromiseState
