Get sum of array columns in JavaScript

Question

We have arrays:

[1, 2, 3, 0]
[1, 2, 3]
[1, 2]

Need to get a one array, indexes which is will be like a sum of columns. Expected result:

[3, 6, 6, 0]

Answer 1

You can use Array.prototype.reduce() in combination with Array.prototype.forEach().

var array = [
        [1, 2, 3, 0],
        [1, 2, 3],
        [1, 2]
    ],
    result = array.reduce(function (r, a) {
        a.forEach(function (b, i) {
            r[i] = (r[i] || 0) + b;
        });
        return r;
    }, []);
document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');