divideArray.js

// Just a simple array division to share with a friend
function divideArray(array, parts) {
    if (parts == 0) return [];
    var length = array.length,
        blockSize = ((length + (length % parts)) / parts),
        blocks = [], i;
    for (i = 0; i < length; i += blockSize) {
        blocks.push(array.slice(i, i + blockSize));
    }
    return blocks;
}

// Now, the QUnit tests I wrote to guide me through implementation
module('dividing');

test('dividing into x columns', function(){
    var referenceArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
    same(divideArray(referenceArray, 2), [[1, 2, 3, 4, 5, 6], [7, 8, 9, 10, 11]], 'two columns');
    same(divideArray(referenceArray, 3), [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11]], 'three columns');
    same(divideArray(referenceArray, 1), [[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]], 'one column');
});

test('dividing with strange elemets', function(){
    var referenceArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
    same(divideArray(referenceArray, 0), [], 'zero');
    same(divideArray([], 5), [], 'empty array');
});