odin-js-fundamentals-part-4/05_sumAll/sumAll.js

const sumAll = function(a, b) {
    if (a < 0 || b < 0 || typeof(a) != "number"|| typeof(b) != "number") {
        return "ERROR";
    }
    let c, sum = 0;
    for ((a > b) ? (i = b, c = a)
                 : (i = a, c = b); i <= c; i++) {
        sum += i;
    }
    return sum;
};

// Do not edit below this line
module.exports = sumAll;