1d array to 2d array of columns

arrayToCols.js

/*
Given an array [0,1,2,3,4] and 3 columns, create:
[ [0,3], [1,4], [2] ] to power a screen that looks like: 0 | 1 | 2
							 3 | 4
*/
var a = [];
for(var i = 0; i < 5; i++) {
    a[i] = i;
}

var amtCols = 3;
var colIdx;
var columns = [];

for(var i = 0, c = a.length; i < c; i++) {
	colIdx = i % amtCols;
	if(!columns[colIdx])
		columns[colIdx] = [];
    
	columns[colIdx].push(a[i]);
}

console.log(columns);