push() won't work as expected in reduce()

Question

Why doesn\'t a.push(b) work in my Array.reduce()? a=a.push(b) where b is a string, turns a to an integer.?!

Answer 1

Since push() returns the new length of the array, you're assigning the length to a. Instead of a conditional operator, use an if statement.

var winner = objKeys.reduce((a, b) => {
    if (frequency[b] === highestVal) {
        a.push(b);
    }
    return a;
}, []);