data-fns/src/lib/getItem.test.ts

This library provides utility functions for working with array data that are useful in many contexts, including creative coding. It offers generic functions that perform common operations such as offsetting an array, generating an array based on a callbac

import { getItem } from "./getItem"

describe('getItem function', () => {
    it('returns the item at the provided index using the provided indexMapFn', () => {
      const myArray = ['a', 'b', 'c', 'd']
      const indexMapFn = (index: number, length: number) => (index + 1) % length
      const item = getItem(3, myArray, indexMapFn)
      expect(item).toBe('a')
    })
  
    it('returns the item at the provided index using a simple indexMapFn', () => {
      const myArray = ['a', 'b', 'c', 'd']
      const indexMapFn = (index: number) => index
      const item = getItem(2, myArray, indexMapFn)
      expect(item).toBe('c')
    })
  
    it('returns the item at the provided index using a complex indexMapFn', () => {
      const myArray = ['a', 'b', 'c', 'd']
      const indexMapFn = (index: number, length: number) => (index * 3 + 1) % length
      const item = getItem(2, myArray, indexMapFn)
      expect(item).toBe('d')
    })
  
    it('wraps around the array if the indexMapFn maps to an index that is out of bounds', () => {
      const myArray = ['a', 'b', 'c', 'd']
      const indexMapFn = (index: number, length: number) => (index + length) % length
      const item = getItem(5, myArray, indexMapFn)
      expect(item).toBe('b')
    })
  })