reverse

function reverseString(str) {
    if (!str || typeof str !== 'string' || str.length < 2)
    return null;
    
    return str.split('').reverse().join('');
}

const reverse2 = (str) => str.split('').reverse().join('');

const reverse3 = (str) => [...str].reverse().join('');


console.log(reverse('abcdefg'));
console.log(reverse2('abcdefg'));
console.log(reverse3('abcdefg'));