function get_products_of_all_ints_except_at_index_verbose(productArray) {
    return productArray.map((value, i, array) => {
        // Wanted to make copies of the array without the element at the current index.
        // .splice returns an array of the deleted items and modifies the original.
        // This is not useful for chaining functions together.
        let newArray = array.slice();
        newArray.splice(i, 1);
        return newArray.reduce((p, x) => p * x);
    });
}

function get_products_of_all_ints_except_at_index_wrong(productArray) {
    return productArray.map((value, i, array) => array.reduce((p, x) => value != x ? p * x : p, 1));
}

function get_products_of_all_ints_except_at_index_good(productArray) {
    return productArray.map((value, i, array) => array.reduce((p, x, j) => i != j ? p * x : p, 1));
}

let get_products_of_all_ints_except_at_index = get_products_of_all_ints_except_at_index_good;

let array = [1, 7, 3, 4];
let result = get_products_of_all_ints_except_at_index(array);
console.log(result);

array = [10, 7, 3, 4, 4];
result = get_products_of_all_ints_except_at_index(array);
console.log(result);