javascript 在 AngularJS 中只注册一次事件监听器
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Register event listener only once in AngularJS
提问by Kitze
I'm broadcasting an event from my navbar controller to another controller, but if I initialize the controller multiple times (when I'm going front and back through the application) the function that executes on my $onevent runs multiple times because it's registered multiple times.
我正在将一个事件从我的导航栏控制器广播到另一个控制器，但是如果我多次初始化控制器（当我前后通过应用程序时）在我的$on事件上执行的函数会多次运行，因为它被多次注册.
$rootScope.$on('submitBookingDialog', function(){
submitBookingDialog();
});
How can I prevent the submitBookingDialog()to happen more than once?
我怎样才能防止这种submitBookingDialog()情况发生不止一次？
I found a solution, but I don't know if it's ideal.
我找到了一个解决方案，但我不知道它是否理想。
回答by DRiFTy
First of all, do you need to send the event on the $rootScope? If not, then you could just register your event handler on the $scope. The event handler will be destroyed whenever your controller scope is destroyed. You would then send the event via $scope.$emitor $scope.$broadcastdepending on your controller hierarchy.
首先，您是否需要在$rootScope? 如果没有，那么您只需在$scope. 每当您的控制器范围被销毁时，事件处理程序就会被销毁。然后，您将通过$scope.$emit或$scope.$broadcast取决于您的控制器层次结构发送事件。
That being said, all you need to do to destroy your event listener is call the deregistration function that is returned when registering the listener:
话虽如此，销毁事件侦听器所需要做的就是调用注册侦听器时返回的注销函数：
var offSubmitBookingDialog = $rootScope.$on('submitBookingDialog', function(){
submitBookingDialog();
});
$scope.$on('$destroy', function() {
// Call the deregistration function when the scope is destroyed
offSubmitBookingDialog();
});
回答by Kim Biesbjerg
This seems to do it for me:
这似乎对我有用：
var removeListener = $rootScope.$on('submitBookingDialog', function(){
submitBookingDialog();
// Remove listener
removeListener();
});回答by Hashbrown
For posterity I ended up doing this:
为了后代，我最终这样做了：
.run(function($rootScope) {
$rootScope.once = function(e, func) {
var unhook = this.$on(e, function() {
unhook();
func.apply(this, arguments);
});
};
})
Because I kept needing to do this in a few places this just ended up being cleaner.
With that on your app module you can now just call onceinstead of $on:
因为我一直需要在几个地方这样做，所以最终变得更干净了。
在您的应用程序模块上使用它，您现在可以调用once而不是$on：
$rootScope.once('submitBookingDialog', function() {
submitBookingDialog();
});
回答by callmehiphop
I ran into a similar situation, so I wrote a small library to make pub/sub stuff easier.
我遇到了类似的情况，所以我写了一个小库，让发布/订阅的东西更容易。
回答by user854301
Maybe you shoud unsubscribe on controller destroy event
也许你应该取消订阅控制器销毁事件
var removeSubmitBookingDialog = $rootScope.$on('submitBookingDialog',submitBookingDialog);
$scope.$on("$destroy", removeSubmitBookingDialog);
