josesaribeiro/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

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

npm install pipe-functions

Usage

Sync

const pipe = require('pipe-functions');

// First argument can be of any type
const result = pipe('input', fn1, fn2, fnN);
// And also a function
const 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.

const pipe = require('pipe-functions');

// First argument can be of any type, as shown in the previous example
pipe('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:

someAsyncFunction('param')
  .then(doSomethingWithTheResult)
  .then(doSomethingElseWithTheResultOfTheLast)
  .then(oneMore)
  .then(almostThere)
  .then(done)
  .catch(console.log)

It could be written as:

const pipe = require('pipe-functions');

pipe(
    someAsyncFunction('param'),
    doSomethingWithTheResult,
    doSomethingElseWithTheResultOfTheLast,
    oneMore,
    almostThere,
    done
).catch(console.log)

Examples

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

Sync

const pipe = require('pipe-functions');

/** Functions **/
const capitalize = v => v[0].toUpperCase() + v.slice(1);
const quote = v => `"${v}"`;

/** Pipe **/
// result will be: "Time"
const result = pipe('time', capitalize, quote);

Async (Promises)

const pipe = require('pipe-functions');

/** Functions **/
// Sync
const capitalize = v => v[0].toUpperCase() + v.slice(1);
// Async
const fetchAndSetBandName = v => new Promise((resolve, reject) => setTimeout(() => resolve(`Pink Floyd - ${v}`), 1000));

/** Pipe **/
// the result will be: Pink Floyd - Time
pipe('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.

const pipe = require('pipe-functions');

/** Functions **/
// Async
const fetchBandName = ({ song }) => new Promise((resolve, reject) =>
setTimeout(() => resolve({ song, band: 'Pink Floyd' }), 1000));
// Sync
const concatBandAndSong = ({ song, band }) => `${band} - ${song}`;

/** Pipe **/
// the result will be: Pink Floyd - Time
pipe('time', fetchBandName, concatBandAndSong).then(console.log)