mselect jquery plugin

prerelease-mselect.js

(function($){

	function collect(a, b) {
		return (a == b ? 0 : (a < b ? -1 : 1));
	}

	function moveSelected(from, to) {
		to.append(from.children('option:selected').remove());
	}

	function moveUpDown(select, direction) {
		selected = select.children('option:selected');
		if(direction == 'up') {
			selected.first().prev().before(selected);
		} else {
			selected.last().next().after(selected);
		}
	}

	function reorder(target) {
		objects = target.find('option');
			sorted = objects.sort(function(a, b) {
				return collect(a.innerHTML, b.innerHTML);
			});
		target.html(sorted);
	}

	function setSelected(jsonURL, left, right) {
		$.getJSON(jsonURL, function(data){
			$.each(data, function(key, value) {
				right.append(left.children('option[value=' + value + ']').remove());
			});
		});
	}

	$.fn.mselect = function(options) {
		// define settings
		var settings = $.extend({
			sort: true, autoSize: false, getJSON: false
		}, options);

		this.each(function() {
			var object = $(this);

			// find selects
			var selects = object.find('select');

			// set multiple attribute
			selects.attr('multiple', true);

			// find buttons
			var buttonsLeftRight = object.find('button.moveLeftRight'),
				buttonsUpDown = object.find('button.moveUpDown');

			// define select inputs and buttons
			var left = selects.eq(0),
				right = selects.eq(1),
				button_left = buttonsLeftRight.eq(0),
				button_right = buttonsLeftRight.eq(1),
				button_up = buttonsUpDown.eq(0),
				button_down = buttonsUpDown.eq(1);

			// initial alphabetic order
			reorder(left);
			// finally some action
			var moveSelectedRight = function() {
				moveSelected(left, right);
			};
			button_left.click(moveSelectedRight);
			left.dblclick(moveSelectedRight);

			var moveSelectedLeft = function() {
				moveSelected(right, left);
				reorder(left);
			};
			button_right.click(moveSelectedLeft);
			right.dblclick(moveSelectedLeft);

			var moveSelectedUp = function() {
				moveUpDown(right, 'up');
			};
			button_up.click(moveSelectedUp);

			var moveSelectedDown = function() {
				moveUpDown(right, 'down');
			};
			button_down.click(moveSelectedDown);

			// autosize
			if (settings.autoSize) {
				w = ((x = left.width())  > (y = right.width())  ? x : y);
				h = ((x = left.height()) > (y = right.height()) ? x : y);
				selects.width(w+10); 
				selects.height(h+40);
			}

			if(settings.getJSON) {
				setSelected(settings.getJSON, left, right);
			}
			// upon post send only selected
			object.parents('form').submit(function() {
				right.find('option').attr('selected', true);
			});
		});
	};
})( jQuery );