extra-promise
v7.0.0
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Utilities for JavaScript Promise and AsyncFunction
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extra-promise
Utilities for JavaScript Promise
and async functions.
Install
npm install --save extra-promise
# or
yarn add extra-promise
API
interface INonBlockingChannel<T> {
send(value: T): void
receive(): AsyncIterable<T>
close: () => void
}
interface IBlockingChannel<T> {
send(value: T): Promise<void>
receive(): AsyncIterable<T>
close: () => void
}
interface IDeferred<T> {
resolve(value: T): void
reject(reason: unknown): void
}
functions
isPromise
function isPromise<T>(val: unknown): val is Promise<T>
function isntPromise<T>(val: T): val is Exclude<T, Promise<unknown>>
isPromiseLike
function isPromiseLike<T>(val: unknown): val is PromiseLike<T>
function isntPromiseLike<T>(val: T): val is Exclude<T, PromiseLike<unknown>>
delay
function delay(timeout: number, signal?: AbortSignal): Promise<void>
A simple wrapper for setTimeout
.
timeout
function timeout(ms: number, signal?: AbortSignal): Promise<never>
It throws a TimeoutError
after ms
milliseconds.
try {
result = await Promise.race([
fetchData()
, timeout(5000)
])
} catch (e) {
if (e instanceof TimeoutError) ...
}
pad
function pad<T>(ms: number, fn: () => Awaitable<T>): Promise<T>
Run a function, but wait at least ms
milliseconds before returning.
parallel
function parallel(
tasks: Iterable<() => Awaitable<unknown>>
, concurrency: number = Infinity
): Promise<void>
Perform tasks in parallel.
The value range of concurrency
is [1, Infinity].
Invalid values will throw Error
.
parallelAsync
function parallelAsync(
tasks: AsyncIterable<() => Awaitable<unknown>>
, concurrency: number // concurrency must be finite number
): Promise<void>
Same as parallel
, but tasks
is an AsyncIterable
.
series
function series(
tasks: Iterable<() => Awaitable<unknown>>
| AsyncIterable<() => Awaitable<unknown>>
): Promise<void>
Perform tasks in order.
Equivalent to parallel(tasks, 1)
.
waterfall
function waterfall<T>(
tasks: Iterable<(result: unknown) => Awatiable<unknown>>
| AsyncIterable<(result: unknown) => Awaitable<unknown>>
): Promise<T | undefined>
Perform tasks in order, the return value of the previous task will become the parameter of the next task. If tasks
is empty, return Promise<undefined>
.
each
function each(
iterable: Iterable<T>
, fn: (element: T, i: number) => Awaitable<unknown>
, concurrency: number = Infinity
): Promise<void>
The async each
operator for Iterable.
The value range of concurrency
is [1, Infinity].
Invalid values will throw Error
.
eachAsync
function eachAsync<T>(
iterable: AsyncIterable<T>
, fn: (element: T, i: number) => Awaitable<unknown>
, concurrency: number // concurrency must be finite number
): Promise<void>
Same as each
, but iterable
is an AsyncIterable
.
map
function map<T, U>(
iterable: Iterable<T>
, fn: (element: T, i: number) => Awaitable<U>
, concurrency: number = Infinity
): Promise<U[]>
The async map
operator for Iterable.
The value range of concurrency
is [1, Infinity].
Invalid values will throw Error
.
mapAsync
function mapAsync<T, U>(
iterable: AsyncIterable<T>
, fn: (element: T, i: number) => Awaitable<U>
, concurrency: number // concurrency must be finite number
): Promise<U[]>
Same as map
, but iterable
is an AsyncIterable
.
filter
function filter<T, U = T>(
iterable: Iterable<T>
, fn: (element: T, i: number) => Awaitable<boolean>
, concurrency: number = Infinity
): Promise<U[]>
The async filter
operator for Iterable.
The value range of concurrency
is [1, Infinity].
Invalid values will throw Error
.
filterAsync
function filterAsync<T, U = T>(
iterable: AsyncIterable<T>
, fn: (element: T, i: number) => Awaitable<boolean>
, concurrency: number // concurrency must be finite number
): Promise<U[]>
Same as filter
, but iterable
is an AsyncIterable
.
all
function all<T extends { [key: string]: PromiseLike<unknown> }>(
obj: T
): Promise<{ [Key in keyof T]: UnpackedPromiseLike<T[Key]> }>
It is similar to Promise.all
, but the first parameter is an object.
const { task1, task2 } = await all({
task1: invokeTask1()
, task2: invokeTask2()
})
promisify
type Callback<T> = (err: any, result?: T) => void
function promisify<Result, Args extends any[] = unknown[]>(
fn: (...args: [...args: Args, callback?: Callback<Result>]) => unknown
): (...args: Args) => Promise<Result>
The well-known promisify
function.
callbackify
type Callback<T> = (err: any, result?: T) => void
function callbackify<Result, Args extends any[] = unknown[]>(
fn: (...args: Args) => Awaitable<Result>
): (...args: [...args: Args, callback: Callback<Result>]) => void
The callbackify
function, as opposed to promisify
.
asyncify
function asyncify<Args extends any[], Result, This = unknown>(
fn: (this: This, ...args: Args) => Awaitable<Result>
): (this: This, ...args: Promisify<Args>) => Promise<Result>
Turn sync functions into async functions.
const a = 1
const b = Promise.resolve(2)
const add = (a: number, b: number) => a + b
// BAD
add(a, await b) // 3
// GOOD
const addAsync = asyncify(add) // (a: number | PromiseLike<number>, b: number | PromiseLike<number>) => Promise<number>
await addAsync(a, b) // Promise<3>
It can also be used to eliminate the call stack:
// OLD
function count(n: number, i: number = 0): number {
if (i < n) return count(n, i + 1)
return i
}
count(10000) // RangeError: Maximum call stack size exceeded
// NEW
const countAsync = asyncify((n: number, i: number = 0): Awaitable<number> => {
if (i < n) return countAsync(n, i + 1)
return i
})
await countAsync(10000) // 10000
spawn
function spawn<T>(
num: number
, create: (id: number) => Awaitable<T>
): Promise<T[]>
A sugar for create multiple values in parallel.
The parameter id
is from 1
to num
.
limitConcurrencyByQueue
function limitConcurrencyByQueue<T, Args extends any[]>(
concurrency: number
, fn: (...args: Args) => PromiseLike<T>
): (...args: Args) => Promise<T>
Limit the number of concurrency, calls that exceed the number of concurrency will be delayed in order.
reusePendingPromises
type VerboseResult<T> = [value: T, isReuse: boolean]
interface IReusePendingPromisesOptions<Args> {
createKey?: (args: Args) => unknown
verbose?: true
}
function reusePendingPromises<T, Args extends any[]>(
fn: (...args: Args) => PromiseLike<T>
, options: IReusePendingPromisesOptions<Args> & { verbose: true }
): (...args: Args) => Promise<VerboseResult<T>>
function reusePendingPromises<T, Args extends any[]>(
fn: (...args: Args) => PromiseLike<T>
, options: IReusePendingPromisesOptions<Args> & { verbose: false }
): (...args: Args) => Promise<T>
function reusePendingPromises<T, Args extends any[]>(
fn: (...args: Args) => PromiseLike<T>
, options: Omit<IReusePendingPromisesOptions<Args>, 'verbose'>
): (...args: Args) => Promise<T>
function reusePendingPromises<T, Args extends any[]>(
fn: (...args: Args) => PromiseLike<T>
): (...args: Args) => Promise<T>
Returns a function that will return the same Promise
for calls with the same parameters if the Promise
is pending.
It generates cache keys based on the options.createKey
function,
The default value of options.createKey
is a stable JSON.stringify
implementation.
Classes
StatefulPromise
enum StatefulPromiseState {
Pending = 'pending'
, Fulfilled = 'fulfilled'
, Rejected = 'rejected'
}
class StatefulPromise<T> extends Promise<T> {
static from<T>(promise: PromiseLike<T>): StatefulPromise<T>
get state(): StatefulPromiseState
constructor(
executor: (
resolve: (value: T) => void
, reject: (reason: any) => void
) => void
)
isPending(): boolean
isFulfilled(): boolean
isRejected(): boolean
}
A subclass of Promise
used for testing, helps you understand the state of Promise
.
Channel
class Channel<T> implements IBlockingChannel<T>
Implement MPMC(multi-producer, multi-consumer) FIFO queue communication with Promise
and AsyncIterable
.
send
Send value to the channel, block until data is taken out by the consumer.receive
Receive value from the channel.close
Close the channel.
If the channel closed, send
and receive
will throw ChannelClosedError
.
AsyncIterator
that have already been created do not throw ChannelClosedError
,
but return { done: true }
.
const chan = new Channel<string>()
queueMicrotask(() => {
await chan.send('hello')
await chan.send('world')
})
for await (const value of chan.receive()) {
console.log(value)
}
BufferedChannel
class BufferedChannel<T> implements IBlockingChannel<T> {
constructor(bufferSize: number)
}
Implement MPMC(multi-producer, multi-consumer) FIFO queue communication with Promise
and AsyncIterable
.
When the amount of data sent exceeds bufferSize
, send
will block until data in buffer is taken out by the consumer.
send
Send value to the channel. If the buffer is full, block.receive
Receive value from the channel.close
Close the channel.
If the channel closed, send
and receive
will throw ChannelClosedError
.
AsyncIterator
that have already been created do not throw ChannelClosedError
,
but return { done: true }
.
const chan = new BufferedChannel<string>(1)
queueMicrotask(() => {
await chan.send('hello')
await chan.send('world')
})
for await (const value of chan.receive()) {
console.log(value)
}
UnlimitedChannel
class UnlimitedChannel<T> implements INonBlockingChannel<T>
Implement MPMC(multi-producer, multi-consumer) FIFO queue communication with Promise
and AsyncIterable
.
UnlimitedChannel
return a tuple includes three channel functions:
send
Send value to the channel. There is no size limit on the buffer, all sending will return immediately.receive
Receive value from the channel.close
Close the channel.
If the channel closed, send
and receive
will throw ChannelClosedError
.
AsyncIterator
that have already been created do not throw ChannelClosedError
,
but return { done: true }
.
const chan = new UnlimitedChannel<string>()
queueMicrotask(() => {
chan.send('hello')
chan.send('world')
})
for await (const value of chan.receive()) {
console.log(value)
}
Deferred
class Deferred<T> implements PromiseLike<T>, IDeferred<T>
Deferred
is a Promise
that separates resolve()
and reject()
from the constructor.
MutableDeferred
class MutableDeferred<T> implements PromiseLike<T>, IDefrred<T>
MutableDeferred
is similar to Deferred
,
but its resolve()
and reject()
can be called multiple times to change the value.
const deferred = new MutableDeferred()
deferred.resolve(1)
deferred.resolve(2)
await deferred // resolved(2)
ReusableDeferred
class ReusableDeferred<T> implements PromiseLike<T>, IDeferred<T>
ReusableDeferred
is similar to MutableDeferred
,
but its internal Deferred
will be overwritten with a new pending Deferred
after each call.
const deferred = new ReusableDeferred()
deferred.resolve(1)
queueMicrotask(() => deferred.resolve(2))
await deferred // pending, resolved(2)
DeferredGroup
class DeferredGroup<T> implements IDeferred<T> {
add(deferred: IDeferred<T>): void
remove(deferred: IDeferred<T>): void
clear(): void
}
LazyPromise
class LazyPromise<T> implements PromiseLike<T> {
then: PromiseLike<T>['then']
constructor(
executor: (resolve: (value: T) => void
, reject: (reason: any) => void) => void
)
}
LazyPromise
constructor is the same as Promise
.
The difference with Promise
is that LazyPromise
only performs executor
after then
method is called.
Semaphore
type Release = () => void
class Semaphore {
constructor(count: number)
acquire(): Promise<Release>
acquire<T>(handler: () => Awaitable<T>): Promise<T>
}
Mutex
type Release = () => void
class Mutex extends Semaphore {
acquire(): Promise<Release>
acquire<T>(handler: () => Awaitable<T>): Promise<T>
}
DebounceMicrotask
class DebounceMicrotask {
queue(fn: () => void): void
cancel(fn: () => void): boolean
}
queue
can create a microtask,
if the microtask is not executed, multiple calls will only queue it once.
cancel
can cancel a microtask before it is executed.
DebounceMacrotask
class DebounceMacrotask {
queue(fn: () => void): void
cancel(fn: () => void): boolean
}
queue
can create a macrotask,
if the macrotask is not executed, multiple calls will only queue it once.
cancel
can cancel a macrotask before it is executed.
TaskRunner
class TaskRunnerDestroyedError extends CustomError {}
class TaskRunner {
constructor(
concurrency: number = Infinity
, rateLimit?: {
duration: number
limit: number
}
)
/**
* @throws {TaskRunnerDestroyedError}
*/
run(task: (signal: AbortSignal) => Awaitable<T>, signal?: AbortSignal): Promise<T>
destroy(): void
}
A task runner, it will execute tasks in FIFO order.