FNional

Functional helper functions

Why me?

Across projects, I noticed I ended up (re-)writing the same set of functions nearly every time. This repo is supposed to be those functions and their flow-typings in one place, so I don't have to copy-paste them over or reinvent them every time.

None of the functions do ground-breaking stuff. I like them 'cause they make my code look a bit prettier and easy to write.

Why me though?

I was never really too happy with the signatures, naming, typing, size or any other property of other available library. Either they offer too much bloat or just aren't what I need. These functions are supposed to be exactly the way I want them.

Also, it's a fun thing to work on every now and then, I suppose.

API

getIn

Returns a property from an object.

getIn: (object: Object, key) => any

Example

const person = {name: 'Stijn Tytgat', nickname: 'stinodes', age: 23}
const age: number = getIn(person, 'age')

getDeep

Returns a deep property from an object (or undefined when not found).

getDeep: (object: Object, keys: Array<*>) => any

Example

const object = {
    property: {
        nestedProperty: 'Nested Value!',
    },
}
const var = getDeep(object, ['property', 'nestedProperty'])

setIn

Returns a new object with the property key set to value.

setIn: (object: Object, key, value) => O

Example

const person = {name: 'Stijn Tytgat', nickname: 'stinodes', age: 23}
const newPerson = setIn(person, 'name', 'Not my true name >:)')

deleteIn

Returns a new object without the property key.

deleteIn: (object: Object, key) => O

Example

const person = {name: 'Stijn Tytgat', nickname: 'stinodes', age: 23}
const personWithoutNickname = deleteIn(person, 'nickname')

shallowMerge

Returns a new object made up of the properties of both passed objects.

shallowMerge: (object: Object1, object: Object2) => {...Object1, ...Object2}

Example

const numbers = {three: 3, two: 2, one: 1}
const letters = {a: a, b: b, c: c}
const numbersAndLetters = shallowMerge(number, letters)

composeReturn

Accepts a function and a value, and returns a new function always returning the passed value, ignoring the original function's return.

composeReturn: (returnValue: R, fn: Params => any) => Params => R

Example

const logger = {log: console.log}
logger.log = composeReturn(logger, log)
logger.log('test')
  .log('test')
  .log('test')
  

onCatch

Calls a callback when an error is thrown.

onCatch: (Params => R, (Error, ...Params) => any) => (Params) => R

Example

const returnString = (value) => {
  if (typeof value !== 'string') throw 'NOT A STRING'
  return value
}
const handled = onCatch(returnString, console.error)
handled('A string')     // callback not called
handled(420)            // callback called

throwIf

Throws the given error if the condition matches

throwIf: (condition: boolean, error: Error|() => Error) => void

Example

const person = {name: 'Stijn'}
const car = {brand: 'Cannot improvise a car brand'}
function validPerson(personObject) {
  return !!personObject.name
}
throwIf(validPerson(person), new Error('This is no person')) // No error
throwIf(validPerson(car), new Error('This is no person'))    // Error!