Vue 3.0 Event API

Vue 3.0 event API

Vue 3.0 introduced a new way of handling events and listeners. Here's a step-by-step tutorial to get you started with the event API in Vue 3.0:

  1. Installation:

    If you haven't installed Vue yet, you can do it by using npm (Node Package Manager). Open your terminal and run the following command:

    npm install -g @vue/cli

    To create a new project, navigate to the folder where you want the project to be and run:

    vue create my-project

    Navigate into the project:

    cd my-project

    Then add Vue 3 to the project:

    vue add vue-next

  2. Creating a Vue component:

    Let's create a basic Vue component that will respond to a button click. Create a new file named MyComponent.vue in the components directory.

    Here's a basic template for MyComponent.vue:

    <template> <button @click="handleClick">Click me!</button> </template> <script> export default { methods: { handleClick() { console.log("Button clicked!"); } } }; </script>

    Here, we've used the @click directive to listen to the click event. When the button is clicked, the handleClick method is triggered.

  3. Using $emit to create custom events:

    In Vue 3, you can create your own custom events using $emit. Here's how to do it:

    <template> <button @click="handleClick">Click me!</button> </template> <script> import { ref } from 'vue'; export default { setup() { const handleClick = () => { emit('my-event', 'Hello world!'); } return { handleClick }; }, emits: ['my-event'] }; </script>

    In this example, we've used the emits option to specify the events that this component can emit. In the handleClick function, we've used $emit to emit our custom event called 'my-event' with a payload of 'Hello world!'.

  4. Listening to custom events:

    You can listen to this custom event in a parent component like so:

    <template> <MyComponent @my-event="handleMyEvent" /> </template> <script> import MyComponent from './components/MyComponent.vue'; export default { components: { MyComponent }, methods: { handleMyEvent(payload) { console.log("my-event was emitted with payload:", payload); } } }; </script>

    Here, we've used the @my-event directive to listen to our custom event. When the 'my-event' is emitted, the handleMyEvent method is triggered with the payload from the event.

This is a basic overview of how the event API works in Vue 3.0. You can use this to create more complex interactions and workflows in your Vue applications.

Examples

  1. Vue 3.0 v-on Directive:

    • The v-on directive is used for attaching event listeners to DOM elements or Vue components.

    • Example code:

      <!-- EventHandling.vue --> <template> <button v-on:click="handleClick">Click me</button> </template> <script> export default { methods: { handleClick() { console.log('Button clicked'); }, }, }; </script>

  2. Custom Events in Vue 3.0:

    • Use custom events to enable communication between parent and child components.

    • Example code:

      <!-- CustomEvents.vue --> <template> <child-component @custom-event="handleCustomEvent"></child-component> </template> <script> import ChildComponent from './ChildComponent.vue'; export default { components: { ChildComponent, }, methods: { handleCustomEvent(data) { console.log('Custom event received with data:', data); }, }, }; </script>

  3. Vue 3.0 Event Modifiers:

    • Event modifiers provide additional functionality to event handling, such as preventing default behavior or stopping event propagation.

    • Example code:

      <!-- EventModifiers.vue --> <template> <form v-on:submit.prevent="handleSubmit"> <button v-on:click.stop="handleClick">Click me</button> </form> </template> <script> export default { methods: { handleSubmit() { console.log('Form submitted'); }, handleClick() { console.log('Button clicked'); }, }, }; </script>

  4. Event Binding in Vue 3.0:

    • Use the v-on directive for event binding to dynamically bind event handlers based on data.

    • Example code:

      <!-- EventBinding.vue --> <template> <button v-on:[eventType]="handleEvent">Click me</button> </template> <script> export default { data() { return { eventType: 'click', }; }, methods: { handleEvent() { console.log('Dynamic event handling'); }, }, }; </script>

  5. Vue 3.0 Custom Event API:

    • Vue 3.0 introduces a custom event API for programmatic event handling and communication between components.

    • Example code:

      <!-- CustomEventAPI.vue --> <template> <button @click="emitCustomEvent">Click me</button> </template> <script> import { ref } from 'vue'; export default { methods: { emitCustomEvent() { this.$emit('custom-event', 'Data from custom event'); }, }, }; </script>

  6. Emitting and Handling Events in Vue 3.0:

    • Use $emit to emit custom events and handle them using v-on.

    • Example code:

      <!-- EmitHandleEvents.vue --> <template> <child-component @custom-event="handleCustomEvent"></child-component> </template> <script> import ChildComponent from './ChildComponent.vue'; export default { components: { ChildComponent, }, methods: { handleCustomEvent(data) { console.log('Custom event received with data:', data); }, }, }; </script>

  7. Vue 3.0 Event Bus:

    • Use an event bus to facilitate communication between unrelated components.

    • Example code:

      <!-- EventBus.vue --> <template> <div> <button @click="emitEvent">Click me</button> <child-component></child-component> </div> </template> <script> import { createApp, ref } from 'vue'; const eventBus = createApp({}); export default { methods: { emitEvent() { eventBus.config.globalProperties.$emit('custom-event', 'Data from event bus'); }, }, }; </script>

  8. Global Event Handling in Vue 3.0:

    • Use the app.config.globalProperties to handle events globally.

    • Example code:

      <!-- GlobalEventHandling.vue --> <template> <button @click="emitGlobalEvent">Click me</button> </template> <script> import { ref } from 'vue'; export default { methods: { emitGlobalEvent() { this.$appContext.config.globalProperties.$emit('global-event', 'Global event data'); }, }, }; </script>

  9. Vue 3.0 Event Propagation:

    • Events in Vue 3.0 propagate from child to parent. Use event.stopPropagation() to stop propagation.

    • Example code:

      <!-- EventPropagation.vue --> <template> <div @click="handleClick"> <child-component @click.stop="handleChildClick"></child-component> </div> </template> <script> import ChildComponent from './ChildComponent.vue'; export default { components: { ChildComponent, }, methods: { handleClick() { console.log('Parent div clicked'); }, handleChildClick() { console.log('Child component clicked'); }, }, }; </script>

  10. Vue 3.0 Native Event Handling:

    • Use native event handling with v-on to respond to browser events.

    • Example code:

      <!-- NativeEventHandling.vue --> <template> <input v-on:input="handleInput" /> </template> <script> export default { methods: { handleInput(event) { console.log('Input value:', event.target.value); }, }, }; </script>

  11. Vue 3.0 Event Arguments:

    • Pass additional arguments to event handlers using the $event special variable.

    • Example code:

      <!-- EventArguments.vue --> <template> <button @click="handleClick('Button clicked')">Click me</button> </template> <script> export default { methods: { handleClick(message) { console.log(message); }, }, }; </script>

  12. Vue 3.0 v-model for Custom Events:

    • Use v-model to create a two-way binding on custom components by emitting and handling update events.

    • Example code:

      <!-- ModelForCustomEvents.vue --> <template> <custom-input v-model="inputValue"></custom-input> </template> <script> import CustomInput from './CustomInput.vue'; export default { components: { CustomInput, }, data() { return { inputValue: '', }; }, }; </script> 
      <!-- CustomInput.vue --> <template> <input :value="value" @input="$emit('update:value', $event.target.value)" /> </template> <script> export default { props: { value: String, }, }; </script>

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