$scope上的watchers和listeners在$scope destroy的时候是否需要手动unregister
这里有讨论: http://stackoverflow.com/questions/25113884/should-angular-watch-be-removed-when-scope-destroyed
结论是: No,you don't need to remove $$watchers,since they will effectively get removed once the scope is destroyed.
From Angular's source code (v1.2.21),Scope's $destroy method:
$destroy: function() { ... if (parent.$$childHead == this) parent.$$childHead = this.$$nextSibling; if (parent.$$childTail == this) parent.$$childTail = this.$$prevSibling; if (this.$$prevSibling) this.$$prevSibling.$$nextSibling = this.$$nextSibling; if (this.$$nextSibling) this.$$nextSibling.$$prevSibling = this.$$prevSibling; ... this.$$watchers = this.$$asyncQueue = this.$$postDigestQueue = [];
So,the $$watchers array is emptied (and the scope is removed from the scope hierarchy).
Removing the watcher from the array is all the unregister function does anyway:
$watch: function(watchExp,listener,objectEquality) { ... return function deregisterWatch() { arrayRemove(array,watcher); lastDirtyWatch = null; }; }
So,there is no point in unregistering the $$watchers "manually".
You should still unregister event listeners though (as you correctly mention in your post) !
NOTE: You only need to unregister listeners registered on other scopes. There is no need to unregister listeners registered on the scope that is being destroyed. E.g.:
// You MUST unregister these $rootScope.$on(...); $scope.$parent.$on(...); // You DON'T HAVE to unregister this $scope.$on(...)
(Thx to @John for pointing it out)
Also,make sure you unregister any event listeners from elements that outlive the scope being destroyed. E.g. if you have a directive register a listener on the parent node or on,then you must unregister them too. Again,you don't have to remove a listener registered on the element being destroyed.
Kind of unrelated to the original question,but now there is also a $destroyed event dispatched on the element being destroyed,so you can hook into that as well (if it's appropriate for your usecase):
link: function postLink(scope,elem) { doStuff(); elem.on('$destroy',cleanUp); }