Array utilities

array-utils.js

// Compares 2 arrays of (primitive) values to see if they are the same
const doArraysMatch = (arr1, arr2) => arr1.length === arr2.length && arr1.every((element) => arr2.includes(element));

// Reusable function to combine arrays
const mergeArr = (...arr) => arr.reduce((acc, val) => [...acc, ...val], []);

// Group an array of objects by a specific key or property value
const movies = [
    { title: 'Test 1', year: 2020 },
    { title: 'Test 2', year: 2020 },
    { title: 'Test 3', year: 2021 }
];

const groupBy = (arr, criteria) => {
    return arr.reduce((acc, currentValue) => {
        if (!acc[currentValue[criteria]]) {
            acc[currentValue[criteria]] = [];
        }
        acc[currentValue[criteria]].push(currentValue);
        return acc;
    }, {});
}

const moviesByYear = groupBy(movies, 'year');