javascript Angularjs 指令删除手表？
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Angularjs directive remove watch?
提问by Harry
I have a $scope.$watchdeclared in the controller of a directive. When I change pages and the directive is removed do I have to manually destroy the way? If so how do I detect when the directive has been removed?
我$scope.$watch在指令的控制器中声明了一个。当我更改页面并删除指令时，是否必须手动销毁该方式？如果是这样，我如何检测指令何时被删除？
回答by Oliver
It depends on the scope, not the directive. If the scope is destroyed, then all its $watchers die with it. On page change your scope'll be destroyed by angular, so you should be safe.
这取决于范围，而不是指令。如果范围被破坏，那么它的所有 $watchers 都会随之消亡。在页面更改时，您的范围将被 angular 破坏，因此您应该是安全的。
When a scope dies it yields a $destroy event. You can watch it:
当范围死亡时，它会产生一个 $destroy 事件。你可以观看：
$scope.$on('$destroy', callback);
and you can manually detach $watchers from the scope, by calling the function it returns:
并且您可以通过调用它返回的函数来手动从作用域中分离 $watchers：
var sentinel = $scope.$watch('expression', callback);
sentinel(); // kill sentinel
You can do this with $on too.
你也可以用 $on 做到这一点。
