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Commit 5a3ca51

Browse files
added folder class promise
1 parent 8fa59bb commit 5a3ca51

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6 files changed

+7440
-0
lines changed

6 files changed

+7440
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node_modules
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MIT License
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Copyright (c) 2022 WebDevSimplified
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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const STATE = {
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FULFILLED: "fulfilled",
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REJECTED: "rejected",
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PENDING: "pending",
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}
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class MyPromise {
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#thenCbs = []
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#catchCbs = []
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#state = STATE.PENDING
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#value
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#onSuccessBind = this.#onSuccess.bind(this)
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#onFailBind = this.#onFail.bind(this)
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constructor(cb) {
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try {
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cb(this.#onSuccessBind, this.#onFailBind)
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} catch (e) {
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this.#onFail(e)
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}
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}
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#runCallbacks() {
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if (this.#state === STATE.FULFILLED) {
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this.#thenCbs.forEach(callback => {
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callback(this.#value)
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})
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this.#thenCbs = []
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}
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if (this.#state === STATE.REJECTED) {
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this.#catchCbs.forEach(callback => {
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callback(this.#value)
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})
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this.#catchCbs = []
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}
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}
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#onSuccess(value) {
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queueMicrotask(() => {
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if (this.#state !== STATE.PENDING) return
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if (value instanceof MyPromise) {
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value.then(this.#onSuccessBind, this.#onFailBind)
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return
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}
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this.#value = value
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this.#state = STATE.FULFILLED
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this.#runCallbacks()
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})
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}
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#onFail(value) {
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queueMicrotask(() => {
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if (this.#state !== STATE.PENDING) return
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if (value instanceof MyPromise) {
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value.then(this.#onSuccessBind, this.#onFailBind)
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return
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}
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if (this.#catchCbs.length === 0) {
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throw new UncaughtPromiseError(value)
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}
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this.#value = value
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this.#state = STATE.REJECTED
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this.#runCallbacks()
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})
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}
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then(thenCb, catchCb) {
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return new MyPromise((resolve, reject) => {
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this.#thenCbs.push(result => {
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if (thenCb == null) {
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resolve(result)
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return
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}
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try {
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resolve(thenCb(result))
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} catch (error) {
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reject(error)
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}
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})
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this.#catchCbs.push(result => {
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if (catchCb == null) {
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reject(result)
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return
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}
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try {
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resolve(catchCb(result))
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} catch (error) {
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reject(error)
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}
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})
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this.#runCallbacks()
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})
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}
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catch(cb) {
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return this.then(undefined, cb)
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}
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finally(cb) {
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return this.then(
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result => {
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cb()
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return result
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},
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result => {
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cb()
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throw result
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}
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)
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}
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static resolve(value) {
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return new Promise(resolve => {
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resolve(value)
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})
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}
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static reject(value) {
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return new Promise((resolve, reject) => {
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reject(value)
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})
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}
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static all(promises) {
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const results = []
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let completedPromises = 0
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return new MyPromise((resolve, reject) => {
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for (let i = 0; i < promises.length; i++) {
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const promise = promises[i]
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promise
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.then(value => {
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completedPromises++
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results[i] = value
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if (completedPromises === promises.length) {
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resolve(results)
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}
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})
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.catch(reject)
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}
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})
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}
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static allSettled(promises) {
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const results = []
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let completedPromises = 0
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return new MyPromise(resolve => {
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for (let i = 0; i < promises.length; i++) {
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const promise = promises[i]
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promise
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.then(value => {
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results[i] = { status: STATE.FULFILLED, value }
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})
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.catch(reason => {
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results[i] = { status: STATE.REJECTED, reason }
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})
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.finally(() => {
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completedPromises++
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if (completedPromises === promises.length) {
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resolve(results)
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}
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})
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}
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})
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}
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static race(promises) {
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return new MyPromise((resolve, reject) => {
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promises.forEach(promise => {
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promise.then(resolve).catch(reject)
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})
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})
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}
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static any(promises) {
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const errors = []
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let rejectedPromises = 0
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return new MyPromise((resolve, reject) => {
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for (let i = 0; i < promises.length; i++) {
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const promise = promises[i]
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promise.then(resolve).catch(value => {
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rejectedPromises++
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errors[i] = value
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if (rejectedPromises === promises.length) {
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reject(new AggregateError(errors, "All promises were rejected"))
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}
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})
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}
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})
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}
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}
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class UncaughtPromiseError extends Error {
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constructor(error) {
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super(error)
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this.stack = `(in promise) ${error.stack}`
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}
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}
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module.exports = MyPromise
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const MyPromise = require("./MyPromise.js")
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// const MyPromise = Promise
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const DEFAULT_VALUE = "default"
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describe("then", () => {
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it("with no chaining", () => {
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return promise().then(v => expect(v).toEqual(DEFAULT_VALUE))
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})
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it("with multiple thens for same promise", () => {
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const checkFunc = v => expect(v).toEqual(DEFAULT_VALUE)
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const mainPromise = promise()
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const promise1 = mainPromise.then(checkFunc)
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const promise2 = mainPromise.then(checkFunc)
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return Promise.allSettled([promise1, promise2])
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})
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it("with then and catch", () => {
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const checkFunc = v => expect(v).toEqual(DEFAULT_VALUE)
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const failFunc = v => expect(1).toEqual(2)
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const resolvePromise = promise().then(checkFunc, failFunc)
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const rejectPromise = promise({ fail: true }).then(failFunc, checkFunc)
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return Promise.allSettled([resolvePromise, rejectPromise])
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})
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it("with chaining", () => {
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return promise({ value: 3 })
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.then(v => v * 4)
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.then(v => expect(v).toEqual(12))
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})
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})
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describe("catch", () => {
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it("with no chaining", () => {
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return promise({ fail: true }).catch(v => expect(v).toEqual(DEFAULT_VALUE))
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})
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it("with multiple catches for same promise", () => {
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const checkFunc = v => expect(v).toEqual(DEFAULT_VALUE)
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const mainPromise = promise({ fail: true })
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const promise1 = mainPromise.catch(checkFunc)
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const promise2 = mainPromise.catch(checkFunc)
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return Promise.allSettled([promise1, promise2])
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})
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it("with chaining", () => {
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return promise({ value: 3 })
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.then(v => {
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throw v * 4
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})
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.catch(v => expect(v).toEqual(12))
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})
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})
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describe("finally", () => {
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it("with no chaining", () => {
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const checkFunc = v => v => expect(v).toBeUndefined()
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const successPromise = promise().finally(checkFunc)
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const failPromise = promise({ fail: true }).finally(checkFunc)
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return Promise.allSettled([successPromise, failPromise])
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})
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it("with multiple finallys for same promise", () => {
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const checkFunc = v => expect(v).toBeUndefined()
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const mainPromise = promise()
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const promise1 = mainPromise.finally(checkFunc)
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const promise2 = mainPromise.finally(checkFunc)
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return Promise.allSettled([promise1, promise2])
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})
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it("with chaining", () => {
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const checkFunc = v => v => expect(v).toBeUndefined()
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const successPromise = promise()
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.then(v => v)
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.finally(checkFunc)
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const failPromise = promise({ fail: true })
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.then(v => v)
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.finally(checkFunc)
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return Promise.allSettled([successPromise, failPromise])
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})
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})
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describe("static methods", () => {
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it("resolve", () => {
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return MyPromise.resolve(DEFAULT_VALUE).then(v =>
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expect(v).toEqual(DEFAULT_VALUE)
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)
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})
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it("reject", () => {
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return MyPromise.reject(DEFAULT_VALUE).catch(v =>
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expect(v).toEqual(DEFAULT_VALUE)
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)
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})
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describe("all", () => {
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it("with success", () => {
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return MyPromise.all([promise({ value: 1 }), promise({ value: 2 })]).then(
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v => expect(v).toEqual([1, 2])
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)
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})
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it("with fail", () => {
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return MyPromise.all([promise(), promise({ fail: true })]).catch(v =>
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expect(v).toEqual(DEFAULT_VALUE)
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)
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})
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})
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it("allSettled", () => {
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return MyPromise.allSettled([promise(), promise({ fail: true })]).then(v =>
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expect(v).toEqual([
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{ status: "fulfilled", value: DEFAULT_VALUE },
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{ status: "rejected", reason: DEFAULT_VALUE },
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])
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)
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})
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describe("race", () => {
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it("with success", () => {
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return MyPromise.race([
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promise({ value: 1 }),
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promise({ value: 2 }),
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]).then(v => expect(v).toEqual(1))
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})
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it("with fail", () => {
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return MyPromise.race([
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promise({ fail: true, value: 1 }),
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promise({ fail: true, value: 2 }),
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]).catch(v => expect(v).toEqual(1))
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})
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})
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describe("any", () => {
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it("with success", () => {
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return MyPromise.any([promise({ value: 1 }), promise({ value: 2 })]).then(
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v => expect(v).toEqual(1)
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)
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})
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it("with fail", () => {
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return MyPromise.any([
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promise({ fail: true, value: 1 }),
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promise({ value: 2 }),
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]).catch(e => expect(e.errors).toEqual([1, 2]))
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})
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})
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})
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function promise({ value = DEFAULT_VALUE, fail = false } = {}) {
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return new MyPromise((resolve, reject) => {
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fail ? reject(value) : resolve(value)
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})
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}

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