This function rotates elements of an array left by d positions. The copy of the array is first destructed and the resulting arrays are then swapped. The length of the original array is subtracted by 1 to keep track of the position of the last element, which is then accessed and the rotElementIndex is set to arrLength-d. The for loop traverses the original array from the first element to the last, and if the count variable is not equal to 0 and the rotElementIndex is within the arrLength-d positions of the last element, the lastElement is inserted into the newArr array. The function then returns the new array.
function rotLeft(a, d) {
let copy = [...a];
let copy2 = [...a].pop();
let newArr = [];
let arrLength = a.length - 1;
let lastElement = copy.pop();
let count = 0;
let rotElementIndex = arrLength - d;
for (let i = 0; i < arrLength; i++) {
if (count === 0 && i===rotElementIndex) {
newArr.push(lastElement);
count++;
i--;
} else {
newArr.push(a[i]);
}
}
return(newArr);
}