How to use event modifier .once in Vue to achieve an event that only fires once

Vue is a popular front-end framework that provides many convenient features, including an event system. Vue's event system allows developers to easily bind events and listen for events. Event modifiers are a feature in the Vue event system that are used to modify the behavior of events. In this article, we will introduce how to use the event modifier .once in Vue to achieve an event that is triggered only once.

What are event modifiers?

Event modifiers are a function in the Vue event system that are used to modify the behavior of events. Vue provides some event modifiers, including .stop, .prevent, .capture, .self, .once, and .passive. These event modifiers can be used by appending the modifier to the event name.

Usage of .once event modifier

.once event modifier is used to realize that the event is triggered only once. For example, if we want to disable a button after it is clicked once, we can use the .once event modifier to achieve this.

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In the above code, we use the .once event modifier to Let the disableButton method be triggered only once. When the button is clicked, the disableButton method will be called, which will then remove the click event handler from the button.

Example of using .once event modifier in Vue

The following is a simple example showing how to use .once event modifier in Vue.

HTML code:

<div id="app">
  <button v-on:click.once="sayHello">点击一次</button>
</div>

JavaScript code:

var vm = new Vue({
  el: '#app',
  methods: {
    sayHello: function () {
      console.log('Hello Vue!');
    }
  }
});

In the above example, we created a Vue instance and bound a click event handler sayHello. This method will be called when the button is clicked and prints the console message "Hello Vue!". Using the .once event modifier, we can ensure that the method is called only once.

Summary

Event modifiers are a function in the Vue event system that are used to modify the behavior of events. Vue provides some event modifiers, including .stop, .prevent, .capture, .self, .once, and .passive. The .once event modifier is used to realize that the event is triggered only once. It can be used by appending the .once modifier to the event name. Using the .once event modifier in Vue can help developers handle events under certain specific circumstances more conveniently.

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