ignoring empty strings when looping through an array in JavaScript

Question

I am attempting to go through an array and add up all the numbers. I used console.log to show me what values the script was using as shown below. I keep trying different variations of things in the if() but nothing seems to be working properly.

    var billycount = 0;
    var billyTotalScore = billyScoreList.reduce(function(score, total) {
        if(score === " ") {
        billycount += 1;
        }
        return +total + +score; 
    });
    console.log(billycount); //0
    console.log(billyTotalScore); //30
    console.log(billyScoreList); // ["12", " ", "18"]
    console.log(billyAverageScore) //10

    var billyAverageScore = billyTotalScore/(billyteamlist.length - billycount);

The answer to billyAverageScore should equal 15 (30/2).

I tried if(score === "0") which gives me the same answers as above and if (score !== true) which gives me a count of 2 and an average of 30. I think reduce() is treating the empty string as a 0. I want to be able to count all the empty strings so I can discount them from the length when finding the average.

I have been wrestling this forever and feel like I'm missing one key concept behind it. Any help would be great! Thanks!

UPDATE:

For anyone who stumbles across this, here is the code I got to work.

var billycount = 0;
    var billyTotalScore = billyScoreList.reduce(function(total, score) {
        if (score === " " || total === " ") {
        billycount++;   
        }
        return +total + +score; 
    });

    var billyAverageScore = billyTotalScore/(billyteamlist.length - billycount);

When I was just checking if (score === " ") I was forgetting that score will never be equal to the first term in the array. I just added || total === " ". the only time this would break down would be if the first element was " " and the second element was 0. I would want to billycount++ for the first element but not for the second. I'll have to give that some more thought.

Answer 1

The callback function of reduce should be function(total, score) instead of function(score, total).

see MDN:

previousValue
    The value previously returned in the last invocation of the callback, or initialValue, if supplied. (See below.)
currentValue
    The current element being processed in the array.