Pony.fm/app/scripts/base/bindonce.js

'use strict';
/**
 * Bindonce - Zero watches binding for AngularJs
 * @version v0.1.1 - 2013-05-07
 * @link https://github.com/Pasvaz/bindonce
 * @author Pasquale Vazzana <pasqualevazzana@gmail.com>
 * @license MIT License, http://www.opensource.org/licenses/MIT
 */

angular.module('pasvaz.bindonce', [])

	.directive('bindonce', function() {
		var toBoolean = function(value) {
			if (value && value.length !== 0) {
				var v = angular.lowercase("" + value);
				value = !(v == 'f' || v == '0' || v == 'false' || v == 'no' || v == 'n' || v == '[]');
			} else {
				value = false;
			}
			return value;
		}

		return {
			restrict: "AM",
			controller: ['$scope', '$element', '$attrs', function($scope, $element, $attrs) {
				var showHideBinder = function(elm, attr, value)
				{
					var show = (attr == 'show') ? '' : 'none';
					var hide = (attr == 'hide') ? '' : 'none';
					elm.css('display', toBoolean(value) ? show : hide);
				}
				var classBinder = function(elm, value)
				{
					if (angular.isObject(value) && !angular.isArray(value)) {
						var results = [];
						angular.forEach(value, function(value, index) {
							if (value) results.push(index);
						});
						value = results;
					}
					if (value) {
						elm.addClass(angular.isArray(value) ? value.join(' ') : value);
					}
				}

				var ctrl =
				{
					watcherRemover : undefined,
					binders : [],
					group : $attrs.boName,
					element : $element,
					ran : false,

					addBinder : function(binder)
					{
						this.binders.push(binder);

						// In case of late binding (when using the directive bo-name/bo-parent)
						// it happens only when you use nested bindonce, if the bo-children
						// are not dom children the linking can follow another order
						if (this.ran)
						{
							this.runBinders();
						}
					},

					setupWatcher : function(bindonceValue)
					{
						var that = this;
						this.watcherRemover = $scope.$watch(bindonceValue, function(newValue)
						{
							if (newValue == undefined) return;
							that.removeWatcher();
							that.runBinders();
						}, true);
					},

					removeWatcher : function()
					{
						if (this.watcherRemover != undefined)
						{
							this.watcherRemover();
							this.watcherRemover = undefined;
						}
					},

					runBinders : function()
					{
						for (var data in this.binders)
						{
							var binder = this.binders[data];
							if (this.group && this.group != binder.group ) continue;
							var value = $scope.$eval(binder.value);
							switch(binder.attr)
							{
								case 'hide':
								case 'show':
									showHideBinder(binder.element, binder.attr, value);
									break;
								case 'class':
									classBinder(binder.element, value);
									break;
								case 'text':
									binder.element.text(value);
									break;
								case 'html':
									binder.element.html(value);
									break;
								case 'src':
								case 'href':
								case 'alt':
								case 'title':
								case 'id':
								case 'style':
								case 'value':
									binder.element.attr(binder.attr, value);
									break;
							}
						}
						this.ran = true;
						this.binders = [];
					}
				}

				return ctrl;
			}],

			link: function(scope, elm, attrs, bindonceController) {
				var value = (attrs.bindonce) ? scope.$eval(attrs.bindonce) : true;
				if (value != undefined)
				{
					bindonceController.runBinders();
				}
				else
				{
					bindonceController.setupWatcher(attrs.bindonce);
					elm.bind("$destroy", bindonceController.removeWatcher);
				}
			}
		};
	});

angular.forEach({
		'boShow' : 'show',
		'boHide' : 'hide',
		'boClass' : 'class',
		'boText' : 'text',
		'boHtml' : 'html',
		'boSrc' : 'src',
		'boHref' : 'href',
		'boAlt' : 'alt',
		'boTitle' : 'title',
		'boId' : 'id',
		'boStyle' : 'style',
		'boValue' : 'value'
	},
	function(tag, attribute)
	{
		var childPriority = 200;
		return angular.module('pasvaz.bindonce').directive(attribute, function()
		{
			return {
				priority: childPriority,
				require: '^bindonce',
				link: function(scope, elm, attrs, bindonceController)
				{
					var name = attrs.boParent;
					if (name && bindonceController.group != name)
					{
						var element = bindonceController.element.parent();
						bindonceController = undefined;
						var parentValue;

						while (element[0].nodeType != 9 && element.length)
						{
							if ((parentValue = element.data('$bindonceController'))
								&& parentValue.group == name)
							{
								bindonceController = parentValue
								break;
							}
							element = element.parent();
						}
						if (!bindonceController)
						{
							throw Error("No bindonce controller: " + name);
						}
					}
					bindonceController.addBinder({element: elm, attr:tag, value: attrs[attribute], group: name});
				}
			}
		});
	});