Object Helper

Functions for working with objects

Installation

npm i @nulltype/object-helper

has

Calls Object.prototype.hasOwnProperty ensuring that the prop is member of object.

import { has } from '@nulltype/object-helper'

function someFunction(arg1: { myprop?: string }, someVar: string) {
  arg1[someVar] = 'test'
  // above line will result in error:
  //   Element implicitly has an 'any' type
  //   because expression of type 'string'
  //   can't be used to index type '{ myprop?: string | undefined; }'.
  //   No index signature with a parameter of type 'string' was found
  //   on type '{ myprop?: string | undefined; }'.ts(7053)

  if (has(arg1, someVar)) {
    arg1[someVar] = 'test' // OK
  }
}

simpleCopy

Use it to copy plain js objects, shortcut for JSON.parse(JSON.stringify(myObject)).

import { simpleCopy } from '@nulltype/object-helper'

const a = { a: 1}
const aCopy = simpleCopy(a)

isSet

Usefull for filter functions when you want to get rid of null and undefined values. Using Boolean() to filter out will still keep the null or undefined types.

const collection = ['a', 'b', null, undefined]
// const collection: (string | null | undefined)[]

const subCollection1 = collection.filter((item) => Boolean(item))
// const subCollection1: (string | null | undefined)[]

const subCollection2 = collection.filter(isSet)
// const subCollection2: string[]