kyu8_sum_without_highest_and_lowest_number.js

/**
 * Task
 * Sum all the numbers of a given array ( cq. list ), except the highest and the lowest element (by value, not by
 * index!);
 * 
 * The highest or lowest element respectively is a single element at each edge, even if there are more than one
 * with the same value;
 * 
 * Mind the input validation;
 * 
 * Example:
 *      { 6, 2, 1, 8, 10 } => 16
 *      { 1, 1, 11, 2, 3 } => 6
 * 
 * Input validation
 * If an empty value ( null, None, Nothing etc. ) is given instead of an array, or the given array is an empty list
 * or a list with only 1 element, return 0;
 * 
 * https://www.codewars.com/kata/576b93db1129fcf2200001e6
 * 
 */


function sumArray(array) {
    function compareNumeric(a, b) {
        if (a > b) return 1;
        if (a == b) return 0;
        if (a < b) return -1;
    }
    
    function add(accumulator, a) {
        return accumulator + a;
    }
    
    if (array == null || array == []) {
        return 0;
    }
    
    array.sort(compareNumeric);
    first = array.shift();
    second = array.pop();
    
    let sum = array.reduce(add, 0);
    return sum;
}