parallelShuffleArrays shuffleArrayOfArrays

gistfile1.js

function parallelShuffleArrays(arrays)
{
	var itemsLeft;
	var selectedItemIndex;
	var temporaryItem;
	var array;

	function useObject()
	{
		//check to see if all arrays are equal lengths
		itemsLeft = getNumberItemsObject(arrays);

		//if the arrays are equal lengths and while there are still items to shuffle
		while(itemsLeft)
		{
			selectedItemIndex = ~~(Math.random() * itemsLeft--);
			for (property in arrays)
			{
				array = arrays[property];
				temporaryItem = array[itemsLeft];
				array[itemsLeft] = array[selectedItemIndex];
				array[selectedItemIndex] = temporaryItem;
			};
			
		}
	}

	function useArray()
	{
		//check to see if all arrays are equal lengths
		itemsLeft = getNumberItemsArray(arrays);

		//if the arrays are equal lengths and while there are still items to shuffle
		while(itemsLeft)
		{
			selectedItemIndex = ~~(Math.random() * itemsLeft--);
			for (var i = 0; i < arrays.length; i++) {
				array = arrays[i];
				temporaryItem = array[itemsLeft];
				array[itemsLeft] = array[selectedItemIndex];
				array[selectedItemIndex] = temporaryItem;
			};
			
		}
	}

	var checkObjectOrArray = Object.prototype.toString.call(arrays);
	if(checkObjectOrArray === "[object Object]")
	{
		useObject();
	}
	else if(checkObjectOrArray === "[object Array]")
	{
		useArray();
	}
}

function shuffleArrayOfArrays(arrays)
{
	var items = getNumberItemsArray(arrays);
	function createArrayList(arr, index)
	{
		var rtnArr = new Array();
		for(property in arr)
		{
			rtnArr.push(arr[property][index])
		}
		return rtnArr;
	}
	for (var i = items - 1; i >= 0; i--) 
	{
		parallelShuffleArrays(createArrayList(arrays, i));
	};

}

function getNumberItemsArray(arrays)
{
	var itemsLeft;
	for (var i = arrays.length - 1; i >= 0; i--)
	{
		if (typeof(itemsLeft) === "undefined")
		{
			itemsLeft = arrays[i].length;
		}
		else if (itemsLeft > arrays[i].length)
		{
			itemsLeft = arrays[i].length;
		}
	};
	return itemsLeft;
}