pipe-functions

Pipe functions in a Unix-like style. It supports Promises (async) anywhere in the pipeline and every step will be executed sequentially. The return (resolve in case of Promises) of each function will be passed in as an argument to the next one

Key features:

• Supports Promises, or any lib following the Promises/A+ spec about being thenable (.then() method)
• Promises will be executed sequentially
• First argument can be of any type (String, Number, Date, etc.) or even a Function or a Promise
• Node.js and Browser ready (to be used on a Browser, without a build step, check lib/pipe-non-es6.js)
• Lightweight, 501 bytes, before gzip!

Install

NPM / Node

1npm install pipe-functions

Usage

Sync

1const pipe = require('pipe-functions');
2
3// First argument can be of any type
4const result = pipe('input', fn1, fn2, fnN);
5// And also a function
6const result2 = pipe(fn0, fn1, fn2, fnN);

Async (Promises)

If the pipeline contains a Promise anywhere in the pipeline, we must treat pipe like a Promise itself, so we must to use .then() to get the final result.

1const pipe = require('pipe-functions');
2
3// First argument can be of any type, as shown in the previous example
4pipe('input', fn1, fnPromise1, fn2, fnPromise2).then(console.log);

A suggestion regarding Promises. Probably you've seen, or had to write, a stack of promises like that:

1someAsyncFunction('param')
2  .then(doSomethingWithTheResult)
3  .then(doSomethingElseWithTheResultOfTheLast)
4  .then(oneMore)
5  .then(almostThere)
6  .then(done)
7  .catch(console.log)

It could be written as:

1const pipe = require('pipe-functions');
2
3pipe(
4    someAsyncFunction('param'),
5    doSomethingWithTheResult,
6    doSomethingElseWithTheResultOfTheLast,
7    oneMore,
8    almostThere,
9    done
10).catch(console.log)

Examples

OBS: Some examples needs a platform with support for Destructuring (Nodejs v6+, Chrome).

Sync

1const pipe = require('pipe-functions');
2
3/** Functions **/
4const capitalize = v => v[0].toUpperCase() + v.slice(1);
5const quote = v => `"${v}"`;
6
7/** Pipe **/
8// result will be: "Time"
9const result = pipe('time', capitalize, quote);

Async (Promises)

1const pipe = require('pipe-functions');
2
3/** Functions **/
4// Sync
5const capitalize = v => v[0].toUpperCase() + v.slice(1);
6// Async
7const fetchAndSetBandName = v => new Promise((resolve, reject) => setTimeout(() => resolve(`Pink Floyd - ${v}`), 1000));
8
9/** Pipe **/
10// the result will be: Pink Floyd - Time
11pipe('time', capitalize, fetchAndSetBandName).then(console.log)

Example with destructuring,

To easily pass in more than one value (within an Object or Array) through the pipeline.

1const pipe = require('pipe-functions');
2
3/** Functions **/
4// Async
5const fetchBandName = ({ song }) => new Promise((resolve, reject) =>
6setTimeout(() => resolve({ song, band: 'Pink Floyd' }), 1000));
7// Sync
8const concatBandAndSong = ({ song, band }) => `${band} - ${song}`;
9
10/** Pipe **/
11// the result will be: Pink Floyd - Time
12pipe('time', fetchBandName, concatBandAndSong).then(console.log)