aseq.mjs

A JavaScript module that allows asynchronous iterators to use array-like methods.

There is also a synchronous version: https://github.com/haiix/seq

Installation

npm install @haiix/aseq

Usage

import aseq from '@haiix/aseq'

Examples

1. By passing the natural number N to the aseq function, an async iterator is created that increments between 0 and N. You can use array-like methods (map, join, etc.) on the created async iterator.

   await aseq(3).join() // "0,1,2"

   await aseq(4).map(x => x + 1).join() // "1,2,3,4"

2. You can pass an async iterable object (with the [Symbol.asyncIterator] method) to the aseq function.

   async function* myFunc () {
     for (let n = 10; n <= 30; n += 10) {
       await new Promise(resolve => setTimeout(resolve, 100))
       yield n
     }
   }
   await aseq(myFunc()).map(x => x + 1).join() // "11,21,31"

3. There are no methods implemented that rewrite themselves. If you want to use those methods, convert them to arrays once. You can use the toArray method for that.

   //aseq(5).reverse() // Error
   (await aseq(5).toArray()).reverse() // [4, 3, 2, 1, 0]

4. In this example, the value is returned when the result of indexOf is found, without waiting for the original processing to finish.

   await aseq(100).map(x => x * 2).filter(x => x % 3 > 0).indexOf(16) // 5

5. The iterator created by the aseq function can be used in a for-await-of statement. Use in processing with side effects.

   for await (const n of aseq(3)) {
     console.log(n) // 0, 1, 2
   }

   for await (const elem of aseq(3).map(n => document.createElement('input'))) {
     document.body.appendChild(elem)
   }