Lotide JavaScript Library

A collection of utility functions inspired by Lodash and Underscore

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 @russell-abraham/lotide

Require it:

const _ = require('@username/lotide');

Call it:

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

Functions

assertArraysEqual(arr1, arr2)

• Description: Compares two arrays and logs a message indicating whether they are equal or not.
• Parameters:
  • arr1 (Array): The first array to compare.
  • arr2 (Array): The second array to compare.
• Returns: None.

assertEqual(actual, expected)

• Description: Compares two values and logs a message indicating whether they are equal or not.
• Parameters:
  • actual (any): The actual value.
  • expected (any): The expected value.
• Returns: None.

assertObjectsEqual(actual, expected)

• Description: Compares two objects for equality and prints an assertion message.
• Parameters:
  • actual (Object): The actual object to compare.
  • expected (Object): The expected object to compare against.
• Returns: void

countLetters(string)

• Description: Counts the occurrences of each letter in a string.
• Parameters:
  • string (string): The input string to count the letters.
• Returns: An object with letters as keys and their respective counts as values.

countOnly(allItems, itemsToCount)

• Description: Counts the occurrences of specific items in an array based on a provided criteria.
• Parameters:
  • allItems (Array): The array of items to be counted.
  • itemsToCount (Object): The object specifying the items to count and their criteria.
• Returns: An object containing the counts of the specified items.

each(obj, iterator, context)

• Description: Iterates over elements of an object or array, calling the iterator function for each element. Supports arrays, array-like strings, and generic objects.
• Parameters:
  • obj (Object|Array|String): The object or array to iterate over.
  • iterator (Function): The iterator function to call for each element.
  • context (Object) (optional): The context object to use as this inside the iterator function.
• Returns: void

eqArrays(arr1, arr2)

• Description: Compares two arrays for equality.
• Parameters:
  • arr1 (Array): The first array to compare.
  • arr2 (Array): The second array to compare.
• Returns: true if the arrays are equal, false otherwise.

eqObjects(object1, object2)

• Description: Checks if two objects have identical keys with identical values.
• Parameters:
  • object1 (Object): The first object to compare.
  • object2 (Object): The second object to compare.
• Returns: Returns true if both objects have identical keys with identical values, otherwise false.

findKey(object, callback)

• Description: Searches for a key in an object based on the callback function's return value.
• Parameters:
  • object (Object): The object to search in.
  • callback (Function): The callback function that is called with each value in the object. It should return a truthy value to find the corresponding key.
• Returns: The found key, or undefined if no key is found.

findKeyByValue(object, value)

• Description: Finds the first key in the object whose value matches the given value.
• Parameters:
  • object (Object): The object to search.
  • value (*): The value to match.
• Returns: The key of the matched value, or undefined if no match is found.

flatten(array)

• Description: Flattens a nested array into a single-level array.
• Parameters:
  • array (Array): The array to flatten.
• Returns: The flattened array.

head(array)

• Description: Returns the first element of an array.
• Parameters:
  • array (Array): The array to query.
• Returns: The first element of the array, or undefined if the array is empty.

letterPositions(sentence)

• Description: Returns an object that maps each letter in the input sentence to an array of its positions.
• Parameters:
  • sentence (string): The input sentence.
• Returns: An object with letter positions.

map(array, callback)

• Description: Applies a callback function to each element in an array and returns an array of the results.
• Parameters:
  • array (Array): The input array.
  • callback (Function): The callback function to apply to each element.
• Returns: An array of the results after applying the callback function to each element.

middle(array)

• Description: Returns the middle element(s) of an array.
• Parameters:
  • array (Array): The array to query.
• Returns: The middle element(s) of the array. If the array has an odd length, returns a single-element array with the middle element. If the array has an even length, returns a two-element array with the two middle elements. If the array has two or fewer elements, returns an empty array.

tail(array)

• Description: Returns a new array with all elements except the first.
• Parameters:
  • array (Array): The array to query.
• Returns: A new array containing all elements except the first, or an empty array if the input array has one or fewer elements.

takeUntil(array, callback)

• Description: Creates a new array with elements from the original array until the callback returns a truthy value.
• Parameters:
  • array (Array): The original array.
  • callback (Function): The callback function that determines the stopping condition. It should return a truthy value to stop iterating.
• Returns: A new array containing the elements until the stopping condition is met.

without(source, itemsToRemove)

• Description: Creates a new array with all occurrences of specified items removed from the source array.
• Parameters:
  • source (Array): The source array.
  • itemsToRemove (Array): The items to remove from the source array.
• Returns: A new array with the specified items removed.

Usage

• Make sure to have Node.js installed.
• Clone the repository and navigate to the project folder.
• Run node filename.js to execute the code and see the test results.