Самописный map

js.js

    const names = ['Denis', 'Ivan', 'Maks', 'Olga']

    function mapArray(arr, fn) {
        let res = []
        for (let i = 0; i < arr.length; i++) {
            res.push(fn(arr[i]));
        }
        return res;
    }

    function nameLength(el) {
        console.log(el)
        return el
    }

    mapArray(names, nameLength)