02-diff-two-arrays.js

/*
Diff Two Arrays:
Compare two arrays and return a new array with any items only found in one of the two given arrays, but not both.
In other words, return the symmetric difference of the two arrays.

Note: You can return the array with its elements in any order.

- diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]) should return an array.
- ["diorite", "andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"] should return ["pink wool"].
- ["diorite", "andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"] should return an array with one item.
- ["andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"] should return ["diorite", "pink wool"].
- ["andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"] should return an array with two items.
- ["andesite", "grass", "dirt", "dead shrub"], ["andesite", "grass", "dirt", "dead shrub"] should return [].
- ["andesite", "grass", "dirt", "dead shrub"], ["andesite", "grass", "dirt", "dead shrub"] should return an empty array.
- [1, 2, 3, 5], [1, 2, 3, 4, 5] should return [4].
- [1, 2, 3, 5], [1, 2, 3, 4, 5] should return an array with one item.
- [1, "calf", 3, "piglet"], [1, "calf", 3, 4] should return ["piglet", 4].
- [1, "calf", 3, "piglet"], [1, "calf", 3, 4] should return an array with two items.
- [], ["snuffleupagus", "cookie monster", "elmo"] should return ["snuffleupagus", "cookie monster", "elmo"].
- [], ["snuffleupagus", "cookie monster", "elmo"] should return an array with three items.
- [1, "calf", 3, "piglet"], [7, "filly"] should return [1, "calf", 3, "piglet", 7, "filly"].
- [1, "calf", 3, "piglet"], [7, "filly"] should return an array with six items.
*/
function diffArray(arr1, arr2) {
    const newArr = [];
    arr1
        .filter(value => !arr2.includes(value))
        .map(value => newArr.push(value));
    arr2
        .filter(value => !arr1.includes(value))
        .map(value => newArr.push(value));
    return newArr;
}

console.log("expects: [4], returns: ", diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]));
console.log("expects: [\"pink wool\"], returns: ", diffArray(["diorite", "andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"]));
console.log("expects: [\"diorite\", \"pink wool\"], returns: ", diffArray(["andesite", "grass", "dirt", "pink wool", "dead shrub"], ["diorite", "andesite", "grass", "dirt", "dead shrub"]));
console.log("expects: [], returns: ", diffArray(["andesite", "grass", "dirt", "dead shrub"], ["andesite", "grass", "dirt", "dead shrub"]));
console.log("expects: [\"piglet\", 4], returns: ", diffArray([1, "calf", 3, "piglet"], [1, "calf", 3, 4]));
console.log("expects: [\"snuffleupagus\", \"cookie monster\", \"elmo\"], returns: ", diffArray([], ["snuffleupagus", "cookie monster", "elmo"]));
console.log("expects: [1, \"calf\", 3, \"piglet\", 7, \"filly\"], returns: ", diffArray([1, "calf", 3, "piglet"], [7, "filly"]));