Remove event listener vue directive

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Remove event listener vue directive

The removeEventListener method removes an event handler that has been attached with the addEventListener method.


Note: To remove event handlers, the function specified with the addEventListener method must be an external function, like in the example above myFunction. Anonymous functions, like " element. For browsers that do not support the removeEventListener method, you can use the detachEvent method.

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Example For browsers that do not support the removeEventListener method, you can use the detachEvent method. HOW TO. Your message has been sent to W3Schools. W3Schools is optimized for learning, testing, and training. Examples might be simplified to improve reading and basic understanding.

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Powered by W3. A String that specifies the name of the event to remove. Note: Do not use the "on" prefix. For example, use "click" instead of "onclick". A Boolean value that specifies the event phase to remove the event handler from. Possible values: true - Removes the event handler from the capturing phase false- Default. Removes the event handler from the bubbling phase Note: If the event handler was attached two times, one with capturing and one bubbling, each must be removed separately.

The useCapture parameter became optional in Firefox 6 and Opera GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. In some situations it is necessary to share state between hook functions on directives. This is particularly useful for directives that attach and detach event listeners on elements.

Consider the following example of a v-drag directive: v-drag. The listener that gets attached to the element requires access to values provided in the bind hook eg elementmodifiers etc. This in itself is not a problem until that same listener has to be removed from the element in the unbind hook. In order to remove the event listener from the element I need to ensure I can get a reference to it from the unbind hook. Perhaps I've gone about this the wrong way, but the only solution I could come up with is registering the listener against it's element in a persistent weakmap in bind and then finding the listener again in unbind using the element.

This problem would be alleviated by simply attaching the listener to this in the bind hook and detaching in unbind by getting the listener from this. Not sure I understand a need for that. Looking at your example, why not just wrap it in a component just handles drag events? Directives are supposed to be for super simple DOM abstractions.

If you need to maintain state between invocations of bind,update,unbindyou can use DOM data attributes.

Directives In Depth

If you need to handle something more complicated than state - like functions - then you're likely better off using a proper component. Directives in Vue 1. The goto solution is to save state in the HTML element, but as sirlancelot said, we want to keep directives simple and limit their responsibility. If they become more complex, using a component is the way to go. Adding to what posva said: Directive had this ability in Vue 1.Directive modifiers are special postfixes that are denoted by a dot, indicating that a directive should be bound in some special way.

The modifiers that are related to events are referred to as event modifiers. Yeah, I know what you are probably thinking. That sounds fancy and all, but what does it actually mean?

Vue Directive & Event Modifiers

So right now I have a div element with a nested button see JSFiddle at the bottomboth having a click event handler which simply invokes a method that shows an alert. If I click the button and close the first alert, notice that a second alert is shown. This is because the click event for the button element propagates up the DOM and thereby triggers the click event on the div element as well. We can disable this default behavior by using an event modifier that corresponds to calling event. We could actually do this too, but embedding that kind of DOM logic into our methods is probably not the best way to go.

remove event listener vue directive

Notice the syntax; I simply added a dot followed by the name of the modifier, after the name of the event. Because of our modifier, event propagation is stopped from here, and thus the click event on the div element is ignored. I will just remove the div element before moving onto the next example.

For whatever reason, we might want to trigger an event only once. This can be accomplished with the once modifier. If I replace the stop modifier with the once modifier, we should see that the alert is only displayed once. So if I add a link that points to Google. This is the same as calling event. Now we will still see the alert, but the browser will no longer send us off to Google.

The only thing this does, is the equivalent of calling event. Before ending this post, I just want to mention that modifiers can be chained, by simply separating the modifiers with dots. I will get back to that in the next post, though.

There are other modifiers too, but these are the ones we need for now.

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Previous Post. Next Post. Featured Learn Vue. Here is what you will learn: How to build advanced Vue. Leave a Reply Cancel reply Your e-mail address will not be published. Website optional.Essentially, a directive is some special token in the markup that tells the library to do something to a DOM element. In Vue. A Vue. Here the prefix is v which is the default. The directive ID is text and the the keypath is message.

This directive instructs Vue. Here we are using a computed expression instead of a single property key. Thanks to async batch updates, even when multiple dependencies change, an expression will only be updated once every event loop. You should use expressions wisely and avoid putting too much logic in your templates, especially statements with side effects with the exception of event listener expressions. To discourage the overuse of logic inside templates, Vue. For bindings that require more complicated operations, use Computed Properties instead.

For security reasons, in inline expressions you can only access properties and methods present on the current context ViewModel and its parents. Some directives require an argument before the keypath or expression. In this example the click argument indicates we want the v-on directive to listen for a click event and then call the clickHandler method of the ViewModel instance.

Filters can be appended to directive keypaths or expressions to further process the value before updating the DOM. Filters are denoted by a single pipe as in shell scripts. For more details see Filters in Depth. You can create multiple bindings of the same directive in a single attribute, separated by commas:.

For example the v-component directive:. Since Vue. This allows you to dynamically resolve the type of component you want to use:. However, note that mustache expressions inside literal directives are evaluated only once. After the directive has been compiled, it will no longer react to value changes. To dynamically instantiate different components at run time, use the v-view directive.

A full list of literal directives can be found in the API reference. For example the v-pre directive:. A full list of empty directives can be found in the API reference.

You can register a global custom directive with the Vue. A definition object can provide several hook functions all optional :. Once registered, you can use it in Vue. When you only need the update function, you can pass in a single function instead of the definition object:. All the hook functions will be copied into the actual directive objectwhich you can access inside these functions as their this context.

The directive object exposes some useful properties:. You should treat all these properties as read-only and refrain from changing them. You can attach custom properties to the directive object too, but be careful not to accidentally overwrite existing internal ones. If you pass in isLiteral: true or isEmpty: true when creating a custom directive, all data-binding work will be skipped for that directive, and only bind and unbind will be called.Instead of binding directly to a method name, we can also use methods in an inline JavaScript statement:.

Result: Say hi Say what. Sometimes we also need to access the original DOM event in an inline statement handler. It is a very common need to call event. Although we can do this easily inside methods, it would be better if the methods can be purely about data logic rather than having to deal with DOM event details. To address this problem, Vue provides event modifiers for v-on. Recall that modifiers are directive postfixes denoted by a dot. Order matters when using modifiers because the relevant code is generated in the same order.

Therefore using v-on:click. Unlike the other modifiers, which are exclusive to native DOM events, the. Vue also offers the. When listening for keyboard events, we often need to check for specific keys. Vue allows adding key modifiers for v-on when listening for key events:.

remove event listener vue directive

You can directly use any valid key names exposed via KeyboardEvent. The use of keyCode events is deprecated and may not be supported in new browsers. Vue provides aliases for the most commonly used key codes when necessary for legacy browser support:. A few keys. You can also define custom key modifier aliases via the global config. You can use the following modifiers to trigger mouse or keyboard event listeners only when the corresponding modifier key is pressed:.

Note that modifier keys are different from regular keys and when used with keyup events, they have to be pressed when the event is emitted. In other words, keyup. If you do want such behaviour, use the keyCode for ctrl instead: keyup. In fact, there are several benefits in using v-on :. This makes it easier to test. When a ViewModel is destroyed, all event listeners are automatically removed. Stay at home and level up. Special Sponsor. Platinum Sponsors.

Learn how to handle events in a free Vue School lesson.Posted by: admin November 2, Leave a comment.

remove event listener vue directive

By listening to this event, you can remove event listeners that might cause memory leaks. Best Practice: Directives should clean up after themselves. You can use element. It will not remove DOM elements or any attached event handlers of the second kind. When element. Sometimes when working with third-party jQuery libraries that remove elements, or if you remove them manually, you might need to perform clean up when that happens:.

A normal case is that a directive is destroyed because ng-view changes the current view.

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Even in this normal case of a directive getting destroyed due to a view changing there are things you might need to manually clean up. If your directive attaches event handlers to elements for example outside the current view, you need to manually clean those up as well:. If you have custom directives that manage the lifecycle of DOM elements etc. Tags: angularangularjslist. January 30, Angularjs Leave a comment. Questions: How to remove Angular template cache once user clicks on logout?

We did thorough research and tried to implement most of the solutions available out there. Questions: I want to listen to the window events in my AngularJS service so that I can broadcast them to my controllers. I have a Chrome extension which sends any message using port. Add menu. Sometimes when working with third-party jQuery libraries that remove elements, or if you remove them manually, you might need to perform clean up when that happens: element.

AngularJS — How to test if a function is called from within another function? Remove Template cache on logout Angular. Listen to window events in an Angularjs service January 30, Angularjs Leave a comment Questions: I want to listen to the window events in my AngularJS service so that I can broadcast them to my controllers. Can an AngularJS controller inherit from another controller in the same module?The EventTarget. The event listener to be removed is identified using a combination of the event type, the event listener function itself, and various optional options that may affect the matching process; see Matching event listeners for removal.

Given an event listener previously added by calling addEventListeneryou may eventually come to a point at which you need to remove it. Obviously, you need to specify the same type and listener parameters to removeEventListenerbut what about the options or useCapture parameters?

Its value must match for removeEventListener to match, but the other values don't. The first call fails because the value of useCapture doesn't match. The second succeeds, since useCapture matches up. Here, we specify an options object in which passive is set to truewhile the other options are left to the default value of false. Now look at each of these calls to removeEventListener in turn. Any of them in which capture or useCapture is true fail; all others succeed. Only the capture setting matters to removeEventListener.

It's worth noting that some browser releases have been inconsistent on this, and unless you have specific reasons otherwise, it's probably wise to use the same values used for the call to addEventListener when calling removeEventListener.

If an EventListener is removed from an EventTarget while it is processing an event, it will not be triggered by the current actions. An EventListener will not be invoked for the event it was registered for after being removed. However, it can be reattached. Calling removeEventListener with arguments that do not identify any currently registered EventListener on the EventTarget has no effect. This example shows how to add a click -based event listener and remove a mouseover -based event listener.

You can work around this by inserting the following code at the beginning of your scripts, allowing the use of addEventListener and removeEventListener in implementations that do not natively support it.

However, this method will not work on Internet Explorer 7 or earlier, since extending the Element. Get the latest and greatest from MDN delivered straight to your inbox. Sign in to enjoy the benefits of an MDN account. The compatibility table on this page is generated from structured data. Last modified: Nov 18,by MDN contributors. Related Topics. Learn the best of web development Get the latest and greatest from MDN delivered straight to your inbox.

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