tubo

Tubo works like the pipe operator more common in functional programming languages, like Elixir.

This lib supports sync and async arguments.

If all arguments are sync functions or literal, the pipeline will run as a normal function returning the last value computed. In case one of the arguments is a function that returns a promise or a promise instance (then-able object), a promise will be returned at the end.

Installation

npm install tubo --save

Usage

Sync

function double(x) {
  return x * 2
}

function square(x) {
  return x * x
}

var output = tubo(
  2,
  double,
  square
)
console.log(output) // => 16

Async

try {
  const result = await tubo(
    bookingDetails.userId,
    fetchUserById, // async
    JSON.parse
  )
  console.log(result)
} catch (error) {
  console.error(error)
}

Async with Promise

tubo(
  bookingDetails.userId,
  fetchUserById, // async
  JSON.parse
)
  .then(function(result) {
    console.log(result)
  })
  .catch(function(error) {
    console.log(error)
  })

Mixed

It is also possible to mix sync and async arguments. Whenever a function that generates promises or a promise intance is found, the lib switchs to async mode and will return a Promise.

Examples

Validation (sync and async)

// Before
function validateEmail(email) {
  email = trim(email)
  validateEmailTld(email)
  validateEmailFormat(email)
}

// After
function validateEmail(email) {
  return tubo(
    email,
    trim,
    validateEmailTld,
    validateEmailFormat
  )
}

try {
  validateEmail('[email protected]')
} catch (error) {
  console.log(error)
}

Straight-forward Cases

// Before
if (cache && localStorage.getItem(endpoint)) {
  return m.prop( JSON.parse( localStorage.get(endpoint) ) )
}

// After
if (cache && localStorage.getItem(endpoint)) {
  return tubo(
    localStorage.get(endpoint),
    JSON.parse,
    m.prop
  )
}

Usage with const

// Before
let items = base64ToJSON(response.data.content)
items = Array.isArray(items) ? items : [items]

// After
const items = tubo(
  base64ToJSON(response.data.content),
  x => Array.isArray(x) ? x : [x]
)

Functional Updates

// Before
return Event.create(
  Object.assign(attrs, { parent_id: parentId, status: 'draft' })
)

// After
return tubo(
  Object.assign(attrs, { parent_id: parentId, status: 'draft' }),
  Event.create
)

Reference and credits

• Ramda.js pipe
• lodash.js flow
• pipe.py
• Some exampes taken from https://github.com/mindeavor/es-pipeline-operator/wiki/Example-Use-Cases

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