Weekly question from Cassidy Williams newsletter (07/06/2021)

lonelyNumber.js

const lonelyNumber = (...numbers) => {
    if (numbers.length !== 3) {
        return console.warn('You must provide 3 numbers.');
    }

    if (numbers.every((item, index, items) => item === items[0])) return 1;


    const lonelyNumbers = numbers.filter((item, index, items) => {
        return items.filter(i => i === item).length === 1;
    })

    if (lonelyNumbers.length === 1) return lonelyNumbers[0];

    return numbers.reduce((acc, curr) => {
        return acc * curr;
    }, 1)

}


console.log(lonelyNumber(...process.argv.slice(2).map(arg => parseInt(arg, 10))));