Implementing Quick Sort is bit tricky but if you understand it and keep on practice it will be easier.

const quickSort = (arr, lo, hi) => {
    if (lo >= hi) {
        return ;
    }

    const pivotIndex = getPivotIndex(arr, lo, hi);
    quickSort(arr, lo, pivotIndex-1);
    quickSort(arr, pivotIndex 1, hi);
}

const getPivotIndex = (arr, lo, hi) => {
    const pivot = arr[hi];
    let idx = lo-1;

    for (let i = lo; i



Try to dry run it you will get the clear picture.