npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

iter-ops

v3.5.0

Published

Basic operations on iterables

Downloads

34,034

Readme

iter-ops

Build Status

About

Basic operations on synchronous + asynchronous iterables, strictly for JavaScript native types.

image

We do not use any synthetic types / wrappers here, like Observable in RXJS, etc. It is strictly an iterable on the input, and an iterable on the output, for maximum performance, simplicity and compatibility (see Rationale).

Related repo: iter-ops-extras - addition to the main API.

Installation

$ npm i iter-ops

Usage

  • Synchronous pipeline:
import {pipe, filter, map} from 'iter-ops';

const input = [1, 2, 3, 4, 5];

const i = pipe(
    input,
    filter((a) => a % 2 === 0), // find even numbers
    map((value) => ({value})) // remap into objects
);

console.log(...i); //=> {value: 2}, {value: 4}
  • Asynchronous pipeline:
import {pipe, toAsync, distinct, delay} from 'iter-ops';

const input = [1, 2, 2, 3, 3, 4];

const i = pipe(
    toAsync(input), // make asynchronous
    distinct(), // emit unique numbers
    delay(1000) // delay each value by 1s
);
// or you can replace `pipe` + `toAsync` with just `pipeAsync`

(async function () {
    for await (const a of i) {
        console.log(a); //=> 1, 2, 3, 4 (with 1s delay)
    }
})();

See also...

API

Function pipe takes any iterable, applies all specified operators to it, and returns an extended iterable. For strict type of iterables, there are also pipeSync and pipeAsync.

Standard Operators:

All standard operators implement the same logic as Array does:

  • concat - merges current iterable with multiple values, iterators or iterables.
  • every - checks if all elements pass the predicate test.
  • filter - standard filter processor, filtering by predicate.
  • flat - flattens/expands sub-iterable elements.
  • flatMap - remaps + flattens sub-iterable elements.
  • map - standard mapping processor, remapping by predicate.
  • reduce - standard reduce processor.
  • some - checks if any element passes the predicate test.

Extended Operators:

  • aggregate - executes an aggregate on accumulated values - see Aggregates.
  • catchError - catches iteration errors - see Error Handling.
  • count - counts values, and produces a one-value iterable.
  • defaultEmpty - adds default to an empty iterable.
  • distinct - emits unique values, with optional key selector.
  • drain - drains the iterable, and then ends it.
  • empty - produces an empty iterable.
  • first - produces a one-value iterable, with the first emitted value.
  • indexBy - emits indexed values that pass the predicate test.
  • isEmpty - produces a one-value iterable, indicating if the source is empty.
  • last - produces a one-value iterable, with the last emitted value.
  • onEnd - notifies of the end of a successful iteration.
  • page - splits values into pages of fixed size (last page can be smaller).
  • repeat - repeats iterable values.
  • skip - starts emitting values after certain count.
  • skipUntil - skips until the predicate returns a truthy value.
  • skipWhile - skips while the predicate returns a truthy value.
  • split - splits values into separate lists - see Split.
  • spread - spreads iterable values.
  • take - emits up to certain number of values.
  • takeLast - emits up to certain number of the last values.
  • takeUntil - emits until the predicate returns a truthy value.
  • takeWhile - emits while the predicate returns a truthy value.
  • tap - taps into each value, without changing the output.
  • timeout - ends iteration after N milliseconds.
  • timing - measures timings for each value.
  • toArray - accumulates values into an array.
  • zip - zips values together, into an array.

Custom Operators:

See iter-ops-extras - a collection of custom operators (ones based on existing operators).

Resources: