Transposing a 2D-array in JavaScript

Question

I\'ve got an array of arrays, something like:

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

I would like to transpose it to get the following

Answer 1

Neat and pure:

[[0, 1], [2, 3], [4, 5]].reduce((prev, next) => next.map((item, i) =>
    (prev[i] || []).concat(next[i])
), []); // [[0, 2, 4], [1, 3, 5]]

Previous solutions may lead to failure in case an empty array is provided.

Here it is as a function:

function transpose(array) {
    return array.reduce((prev, next) => next.map((item, i) =>
        (prev[i] || []).concat(next[i])
    ), []);
}

console.log(transpose([[0, 1], [2, 3], [4, 5]]));

Update. It can be written even better with spread operator:

const transpose = matrix => matrix.reduce(
    ($, row) => row.map((_, i) => [...($[i] || []), row[i]]), 
    []
)