SOURCE

const arr =[1,2,3,4,5,6,7];
function rotate(arr,k){
    let length = arr.length;
    if(!k || !length) return arr;
    for(let i=0;i<k;i++){
        const n = arr.pop();
        if(n){
            arr.unshift(n);
        }
    }
    return arr;
}
// console.log(rotate(arr,3));

function rotate2(arr,k){
    let length = arr.length;
    if(!k || !length) return arr;
    const arr1 = arr.slice(-k);
    const arr2 = arr.slice(0,length-k);
    return arr1.concat(arr2)
}
console.log(rotate2(arr,3));