getSum.js

//Get the sum of all the numbers between a and b

function GetSum( a,b )
{
    sum = 0;
    
    if(a<b){
        for (let i = a; i <= b; i++) {
            sum += i;    
        }
    }else if(b<a){
        for (let i = b; i <= a; i++) {
            sum += i;    
        }
    }else{
        return a;
    }

    return sum;

}