@tai-de/lotide NPM

Lotide JS Library

A mini clone of the Lodash library.

Purpose

BEWARE: This library was published for learning purposes. It is not intended for use in production-grade software.

This project was created and published by me as part of my learnings at Lighthouse Labs.

Usage

Install it:

npm install @tai-de/lotide

Require it:

const _ = require('@tai-de/lotide');

Call it:

const results = _.tail([1, 2, 3]) // => [2, 3]

Equality checks

Functions used to compare, returning true or false.

eqArrays(arrayOne, arrayTwo)

Returns true or false after checking if the arrays are equal
- Supports nested arrays & array items being objects using recursion
arrayOne and arrayTwo can be given any array arguments

eqObjects(object1, object2)

Returns true or false after checking if two objects are equal
- Supports arrays as object values & nested objects using recursion
object1 and object2 can be given any array arguments

Assertion functions

Functions used to return Assertion Passed or Assertion Failed whether two arguments are equal.

assertEqual(actual, expected)

Returns Assertion Passed or Assertion Failed after checking if the passed arguments are equal.
actual and expected can be given any argument (primitive values. see below for Array and Object variants)

assertArraysEqual(actual, expected)

Returns Assertion Passed or Assertion Failed after checking if the two arrays are equal.
actual and expected can be given any two arrays as arguments

assertObjectsEqual(actual, expected)

Returns Assertion Passed or Assertion Failed after checking if the two objects are equal.
actual and expected can be given any two objects as arguments

String functions

Functions used to manipulate or parse a string

countLetters(string)

An object will be returned containing counts of all unique letters in the string
- Spaces are excluded/trimmed from the input
countLetters("Hello") => { h: 1, e: 1, l: 2, o: 1 }

letterPositions(string)

An object will be returned containing the index positions of all unique letters in the string
- Spaces are excluded from the output, but do contribute to the positions
letterPositions("hello") => { h: [0], e: [1], l: [2,3], o: [4] }
letterPositions("lighthouse in the house") => { l: [0], i: [1, 11], g: [2], h: [3, 5, 15, 18], t: [4, 14], o: [6, 19], u: [7, 20], s: [8, 21], e: [9, 16, 22], n: [12] }

Array functions

Functions used to manipulate or parse an array

countOnly(array, object)

An object will be returned containing counts of everything within the array that the object parameter listed as true
- If the object lists true for a key that does not exist in the array, include an undefined value in the object output
countOnly(["Jason", "Jason", "Fang", "Agouhanna"], { "Jason": true, "Karima": true, "Fang": true, "Agouhanna": false }) => { Jason: 2, Karima: undefined, Fang: 1 }

flatten(array)

Returns a new array after doing a flattening of any nested values/arrays
flatten([1, 2, [3, 4], 5, [6]]) => [1, 2, 3, 4, 5, 6]
flatten([1, 2, [3, 4, [5, 6, [7, 8, [[[[[9, [10]]]]]]]]]]) => [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

head(array)

Returns the head (first value) in a given array
head(["Hello", "Lighthouse", "Labs"]) => "Hello"

middle(array)

Returns the middle value of an array
- If array length is less than 2, return empty array
- If array length is odd, return exact middle value
- If array length is even, return middle two values
middle([1]) => []
middle([1, 2, 3]) => [2]
middle([1, 2, 3, 4]) => [2, 3]

tail(array)

Returns the tail (array minus head) in a given array
head(["Hello", "Lighthouse", "Labs"]) => ["Lighthouse", "Labs"]

without(array, itemsToRemove)

Parses array and returns a new array that excludes all of the values passed through itemsToRemove
without([1, 2, 3], [1]) => [2, 3]
without(["1", "2", "3"], [1, 2, "3"]) => ["1", "2"]

map(array, callBackFn)

Mimics .map() behavior and applies the callBackFn argument against the array items
map(["never", "gonna", "give", "you", "up"], word => word[0]) = ["n", "g", "g", "y", "u"]

takeUntil(array, callBackFn)

Loops through a given array until the condition in the callBackFn returns true. A new array is returned with the preceeding values.

const data1 = 1, 2, 5, 7, 2, -1, 2, 4, 5;

takeUntil(data1, x => x < 0) => [1, 2, 5, 7, 2]

const data2 = "I've", "been", "to", "Hollywood", ",", "I've", "been", "to", "Redwood"";

takeUntil(data1, x => x < 0) => ['I've', 'been', 'to', 'Hollywood']

Object functions

Functions used to manipulate or parse an object

findKey(object, callback)

Given an object of single key/value pairs, this will return the first key where the value is found
- If no matching key is found for the value, return undefined

const data = {\ "Blue Hill": { stars: 1 },\ "Akaleri": { stars: 3 },\ "noma": { stars: 2 },\ "elBulli": { stars: 3 },\ "Ora": { stars: 2 },\ "Akelarre": { stars: 3 }\ }

findKey(data, x => x.stars === 2) => "noma"

findKeyByValue(object, value)

Given an object of single key/value pairs, this will return the first key where the value is found
- If no matching key is found for the value, return undefined