AsyncArray
is a class that inheriths from Array
and adds async
methods with support for async
callbacks such as
asyncForEach
, asyncMap
etc:
const existing = await AsyncArray.of(1, 2, 3)
.asyncFilter(async (id) => existsInDatabase(id))
npm install @ziggy42/async-array
The constructor of AsyncArray
behaves exactly like Array
. From MDN:
A JavaScript array is initialized with the given elements, except in the case where a single argument is passed to the Array constructor and that argument is a number.
If the only argument passed to the Array constructor is an integer between 0 and 232-1 (inclusive), this returns a new JavaScript array with its length property set to that number (Note: this implies an array of arrayLength empty slots, not slots with actual undefined values). If the argument is any other number, a RangeError exception is thrown.
const arr1 = new AsyncArray(1, 2, 3) // AsyncArray [ 1, 2, 3 ]
const arr2 = new AsyncArray(3) // AsyncArray [ <3 empty items> ]
There are also two static functions to create new AsyncArray
instances:
const arr1 = AsyncArray.of(1, 2, 3) // AsyncArray [ 1, 2, 3 ]
const arr2 = AsyncArray.from([1, 2, 3]) // AsyncArray [ 1, 2, 3 ]
A regular Array
can be obtained form an AsyncArray
:
const arr = AsyncArray.of(1, 2, 3).toArray() // [ 1, 2, 3 ]
AsyncArray
adds the following methods:
asyncEvery
asyncFilter
asyncFind
asyncFindIndex
asyncFlatMap
asyncForEach
asyncMap
asyncReduce
asyncReduceRight
asyncSome
These methods behave exactly like the non-async versions but they accept async callbacks.
const existing = await AsyncArray.of('1', '2', '3')
.asyncFilter(async (id) => existsInDatabase(id))
Be aware that the async callbacks are executed in sequence, NOT in parallel. The following methods allow you to execute the callbacks in parallel instead:
asyncFilterAll
asyncMapAll
const existing = await AsyncArray.of(1, 2, 3)
.asyncFilterAll(async (id) => existsInDatabase(id))