Toolbox

Some useful functions and types.

Motivation

Set of functions and types used across the different projects of Productive Codebases.

Prerequisites

Typescript is not mandatory but highly recommended.

Installation

npm install @productive-codebases/toolbox

Exposed tooling

Functions

isDefined

Rturn true if the value is neither null nor undefined.

Usage:

if (isDefined(x)) {
  //...
}

isTruthy

Return true if the value is truthy.

Usage:

if (isTruthy(x)) {
  //...
}

ensureArray

Ensure that a value is an array.

Usage:

ensureArray(x).map(...)

ensureSet

Ensure that a value is a set.

Usage:

ensureSet(x).forEach(...)

deepMerge

Merge deeply multiple objects.

Usage:

const mergedObjects = deepMerge([object1, object2], optionalOptions)

indexEntitiesToMap, appendEntitiesToMap

Index / Append entities (objects) to a map.

Usage:

const entities = indexEntitiesToMap(entitiesAsArray, 'id')
const entityId1 = entities.get('1')

addSetValueToMap, removeSetValueToMap

Add or remove a value to a set, indexed by a key.

Usage:

const map = new Map()
addSetValueToMap(map, '1', 'value')
const set = map.get('1')

assertUnreachableCase

Allow to ensure that all cases of a switch are implemented by returning a never type in the default case.

Usage:

switch (unionOfValues) {
  case 'value1': {
    // ...
  }

  case 'value2': {
    // ...
  }

  default: {
    assertUnreachableCase(unionOfValues)
  }
}

MetaData

Container allowing to store typed metadata.

Usage:

interface IMetaData {
  data: string
}

const metadata = new MetaData<IMetaData>()
metadata.set({ data: 'foo' })
const value = metadata.get('data')

setupLogger

Return a composite function allowing to log message from a defined logger mapping.

const loggerMapping = {
  server: {
    express: 'express',
    middleware: 'middleware'
  },
  client: {
    react: 'react',
    store: 'store'
  }
}

const { newLogger } = setupLogger(loggerMapping)
const logger = newLogger('server')('middleware')

logger('info')('Send request')
logger('error')('Error 500')

You can enable / disable logger messages by adding a debug property in local storage. Example:

// Will show only log messages for the server middleware:
localStorage.set('debug', 'server:middleware:*')

Types

Maybe

Define a value that can be null.

Usage:

type Value = Maybe<string>

MaybeUndef

Define a value that can be undefined.

Usage:

type Value = MaybeUndef<string>

Perhaps

Define a value that can be null or undefined.

Usage:

type Value = Perhaps<string>

PropertiesNullable

Define an object with all properties as nullable values.

Usage:

interface IUser = {
  id: number
  name: string
}

const user: PropertiesNullable<IUser> = {
  id: null,
  name: null
}

PropertiesNonNullable

Define an object with all properties as non-nullable values.

Usage:

interface INullableUser = {
  id: Maybe<number>
  name: Maybe<string>
}

const user: PropertiesNonNullable<INullableUser> = {
  id: 1,
  name: null  // Error
}