pacit

make JavaScript chainable and more readable.

How to use

Install

npm install --save pacit
# or 
yarn add pacit

API

There are only 4 methods you should notice.

• pacit pack a value

import pacit from 'pacit'
 
pacit(123) // pack a number
pacit('test') // pack a string
pacit({ foo: 'bar' }) // pack an object
pacit([123]) // pack an array

• map map the value to another. It accepts a pure function.

const addOne = (n: number) => n + 1
const result = pacit(123)
  .map(addOne)
  .valueOf()
 
console.log(result) // 124

• and execute some side effect here. It returns the original value whatever the return value of the function you pass in is.

You can get rid of any and at any time.

const result = pacit(123)
  .map(addOne)
  .and(console.log) // 124
  .map(addOne)
  .and(console.log) // 125
  .and(addOne) // nothing happends here
  .valueOf()
 
console.log(result) // 125

• valueOf unpack and get the value in it

pacit(123)
  .map(addOne)
  .valueOf() // return 124

Why This

For last few years, I was constantly trying to make JavaScript more functional. I used underscore, lodash and ramda and all of them are nice.

However, recently I found JavaScript might be not so functional, despite of somewhat features of functional programming supported.

Suppose we need to reverse digits of a given integer. We probably do like this if using basic JavaScript.

Basic JavaScript

function solution(num) {
  const str = String(num)
  const arr = str.split('')
  const reversedArr = arr.reverse()
  const reversedStr = arr.join('')
 
  return parseInt(reversedStr)
}

Annoying! We have to make up 4 names for these variables. Or we can merge some actions

function solution(num) {
  const str = String(num)
  const reversed = str
    .split('')
    .reverse()
    .join('')
 
  return parseInt(reversed)
}

More clearer huh! But we still have to make up two names at least. Let try with Ramda

Ramda

const solution = R.pipe(String, R.reverse, parseInt))

Pretty good! I used to love this way. Because of the limitation of TypeScript, the pipe methods cannot accept too many arguments.

Pacit

As I use React, I tend to focus on data only.

const solution = (num: number) =>
  pacit(num)
    .map(String)
    .add(console.log) // You can use `add` anywhere you like. Since it will not affect the value, it's easy to be removed.
    .map(R.reverse)
    .add(alert)
    .map(parseInt)
    .valueOf()