parent.vue
<template>
<input :type="computedType"/>
</template>
<script setup>
import { ref, computed } from 'vue';
const props = defineProps({
type: {
required: false,
type: String,
default: 'text',
},
});
const showPassword = ref(false);
const computedType = computed(() => {
if (props.type === 'password') {
return showPassword.value ? 'text' : 'password';
}
return props.type;
});
</script>
<script>
export default {
data() {
return {
uuid: getRandomUuid(),
}
}
}
</script>
child.vue
<template>
<input :type="computedType"/>
</template>
<script>
import Parent from '~/components/parent.vue'
export default {
extends: Parent
}
</script>
In Vue3, I have a child.vue component which is inherited from parent.vue, I defined a computedType computed attribute in parent.vue, but it's missing in child.vue, however, uuid which is defined in parent.vue is accessible in child.vue.
[Vue warn]: Property "computedType" was accessed during render but is not defined on instance.
How to get computedType and any other attributes defined in <script setup> of parent.vue in child.vue?
Really appreciate any help provided!
update:
Only if I define all the attributes in <script>(but not in setup()) instead of <script setup>, they could be accessible
There are a few specific instances where you can have more than one script tag, and they are all outlined here in the documentation. Still, besides those 3 specific use cases, you shouldn't use more than one script tag. Your case of a separate script tag for one data variable is not a valid use case.
I recommend writing the component entirely with the options API (the only API that supports the "extends" option), or writing entirely with the composition API where you would use composable functions to effectively extend your component
defineExpose({computedType});
try this
I have a weird situation with my Vue3 component. I am trying to get a value from the props inside the setup() function. But this returns nothing.
<template>
<div class="border p-2 space-y-2">
<h2 class="text-center">Makers</h2>
{{ product.makers }}
</div>
</template>
<script>
import { ref, onMounted, toRef, toRefs } from 'vue'
import ProductStore from '../store/ProductStore'
export default {
props: {
product: Object
},
setup(props) {
console.log(props.product.makers)
},
}
</script>
The value is sent from another component like the one below
<ProductMakers :product="product"/>
But I always get undefined as my response. Any clue to resolve this problem? Am I missing something?
To my surprise, the template is always showing the value correctly. The problem is only inside the setup(). Any clue?
This means that product is reactively updated after the creation of component instance.
Updated value is supposed to be accessed in a watcher or a computed. In case a side effect like logging is needed, this is the case for a watcher:
setup(props) {
watchEffect(() => {
if (props.product.makers)
console.log(props.product.makers)
});
},
(I'm new to vue and nuxt).
I currently have a <HeaderImage> component in my layouts/default.vue and would like to have each page to pass a different image url to that component.
Right now I'm using vuex $store for that purpose (but would love if there were a simpler way to pass the data), but I'm trying to figure out where in my pages/xyz.vue I should be using the mutation this.$store.commit('headerImg/setHeaderImage', 'someImage.jpg')
All of the examples I can find only use mutations on user events.
What you are trying to do probably doesn't have a particularly simple solution and how I would do it is use a store state element that is set by the component when it is loaded. The component would commit a mutation in the store that alters the state element. The layout would then use that state element through a getter to set the image url. Here is how I'd code that. In the store state i'd have an array of class names, let's call it 'headState', and an element that would be assigned one of those class names, called 'headStateSelect:
//store/index.js
state: {
headState: ['blue', 'red', 'green'],
headStateSelect : ''
}
In your component you can use fetch, or async fetch to commit a mutation that will set 'headStateSelect' with one of the 'headState' elements.
//yourComponent.vue
async fetch ({ store, params }) {
await store.commit('SET_HEAD', 1) //the second parameter is to specify the array position of the 'headState' class you want
}
and store:
//store/index.js
mutations: {
SET_HEAD (state, data) {
state.headStateSelect = state.headState[data]
}
}
In the store we should also have a getter that returns the 'headStateSelect' so our layout can easily get it.
getters: {
head(state) {
return state.headStateSelect
}
}
finally, in the layout we can use the computed property to get our getter:
//layouts/default.vue
computed: {
headElement() {
return this.$store.getters.head
}
}
and the layout can use the computed property to set a class like so:
//layouts/default.vue
<template>
<div :class="headElement">
</div>
</template>
The div in the layout will now be set with the class name 'red' (ie. store.state.headState[1]) and you can have a .red css class in your layout file that styles it however you want, including with a background image.
For now I've settled on creating it like this:
~/store/header.js
import Vue from 'vue'
import Vuex from 'vuex'
Vue.use(Vuex)
const state = () => ({
headerImage: 'default.jpg'
})
const mutations = {
newHeaderImage(state, newImage) {
state.headerImage = newImage
}
}
export default {
namespaced: true,
state,
mutations
}
``
~/layouts/default.vue
<template>
<div id="container">
<Header />
<nuxt />
</div>
</template>
<script>
import Header from '~/components/Header'
export default {
components: {
Header
}
}
</script>
``
~/components/Header.vue
<template>
<header :style="{ backgroundImage: 'url(' + headerImage + ')'}" class="fixed">
<h1>Header Text</h1>
</header>
</template>
<script>
computed: {
var image = this.$store.state.header.headerImage
return require('~/assets/img/' + image)
}
</script>
``
~/pages/customHeader.vue
<template>
<main>
...
</main>
</template>
<script>
export default {
head() {
this.$store.commit('header/newHeaderImage', 'custom-header.jpg')
return {
title: this.title
}
}
}
</script>
But something feels off about putting the mutation in head() Is that correct?
And the next issue I am facing is how to return the header to default.jpg if a page doesn't change the state (which makes me think this is all the wrong approach).
Let's say I have a main Vue instance that has child components. Is there a way of calling a method belonging to one of these components from outside the Vue instance entirely?
Here is an example:
var vm = new Vue({
el: '#app',
components: {
'my-component': {
template: '#my-template',
data: function() {
return {
count: 1,
};
},
methods: {
increaseCount: function() {
this.count++;
}
}
},
}
});
$('#external-button').click(function()
{
vm['my-component'].increaseCount(); // This doesn't work
});
<script src="http://vuejs.org/js/vue.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="app">
<my-component></my-component>
<br>
<button id="external-button">External Button</button>
</div>
<template id="my-template">
<div style="border: 1px solid; padding: 5px;">
<p>A counter: {{ count }}</p>
<button #click="increaseCount">Internal Button</button>
</div>
</template>
So when I click the internal button, the increaseCount() method is bound to its click event so it gets called. There is no way to bind the event to the external button, whose click event I am listening for with jQuery, so I'll need some other way to call increaseCount.
EDIT
It seems this works:
vm.$children[0].increaseCount();
However, this is not a good solution because I am referencing the component by its index in the children array, and with many components this is unlikely to stay constant and the code is less readable.
In the end I opted for using Vue's ref directive. This allows a component to be referenced from the parent for direct access.
E.g.
Have a component registered on my parent instance:
var vm = new Vue({
el: '#app',
components: { 'my-component': myComponent }
});
Render the component in template/html with a reference:
<my-component ref="foo"></my-component>
Now, elsewhere I can access the component externally
<script>
vm.$refs.foo.doSomething(); //assuming my component has a doSomething() method
</script>
See this fiddle for an example: https://jsfiddle.net/0zefx8o6/
(old example using Vue 1: https://jsfiddle.net/6v7y6msr/)
Edit for Vue3 - Composition API
The child-component has to return the function in setup you want to use in the parent-component otherwise the function is not available to the parent.
Note: <sript setup> doc is not affacted, because it provides all the functions and variables to the template by default.
You can set ref for child components then in parent can call via $refs:
Add ref to child component:
<my-component ref="childref"></my-component>
Add click event to parent:
<button id="external-button" #click="$refs.childref.increaseCount()">External Button</button>
var vm = new Vue({
el: '#app',
components: {
'my-component': {
template: '#my-template',
data: function() {
return {
count: 1,
};
},
methods: {
increaseCount: function() {
this.count++;
}
}
},
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<my-component ref="childref"></my-component>
<button id="external-button" #click="$refs.childref.increaseCount()">External Button</button>
</div>
<template id="my-template">
<div style="border: 1px solid; padding: 2px;" ref="childref">
<p>A counter: {{ count }}</p>
<button #click="increaseCount">Internal Button</button>
</div>
</template>
For Vue2 this applies:
var bus = new Vue()
// in component A's method
bus.$emit('id-selected', 1)
// in component B's created hook
bus.$on('id-selected', function (id) {
// ...
})
See here for the Vue docs.
And here is more detail on how to set up this event bus exactly.
If you'd like more info on when to use properties, events and/ or centralized state management see this article.
See below comment of Thomas regarding Vue 3.
You can use Vue event system
vm.$broadcast('event-name', args)
and
vm.$on('event-name', function())
Here is the fiddle:
http://jsfiddle.net/hfalucas/wc1gg5v4/59/
A slightly different (simpler) version of the accepted answer:
Have a component registered on the parent instance:
export default {
components: { 'my-component': myComponent }
}
Render the component in template/html with a reference:
<my-component ref="foo"></my-component>
Access the component method:
<script>
this.$refs.foo.doSomething();
</script>
Say you have a child_method() in the child component:
export default {
methods: {
child_method () {
console.log('I got clicked')
}
}
}
Now you want to execute the child_method from parent component:
<template>
<div>
<button #click="exec">Execute child component</button>
<child-cmp ref="child"></child_cmp> <!-- note the ref="child" here -->
</div>
</template>
export default {
methods: {
exec () { //accessing the child component instance through $refs
this.$refs.child.child_method() //execute the method belongs to the child component
}
}
}
If you want to execute a parent component method from child component:
this.$parent.name_of_method()
NOTE: It is not recommended to access the child and parent component like this.
Instead as best practice use Props & Events for parent-child communication.
If you want communication between components surely use vuex or event bus
Please read this very helpful article
This is a simple way to access a component's methods from other component
// This is external shared (reusable) component, so you can call its methods from other components
export default {
name: 'SharedBase',
methods: {
fetchLocalData: function(module, page){
// .....fetches some data
return { jsonData }
}
}
}
// This is your component where you can call SharedBased component's method(s)
import SharedBase from '[your path to component]';
var sections = [];
export default {
name: 'History',
created: function(){
this.sections = SharedBase.methods['fetchLocalData']('intro', 'history');
}
}
Using Vue 3:
const app = createApp({})
// register an options object
app.component('my-component', {
/* ... */
})
....
// retrieve a registered component
const MyComponent = app.component('my-component')
MyComponent.methods.greet();
https://v3.vuejs.org/api/application-api.html#component
Here is a simple one
this.$children[indexOfComponent].childsMethodName();
I am not sure is it the right way but this one works for me.
First import the component which contains the method you want to call in your component
import myComponent from './MyComponent'
and then call any method of MyCompenent
myComponent.methods.doSomething()
Declare your function in a component like this:
export default {
mounted () {
this.$root.$on('component1', () => {
// do your logic here :D
});
}
};
and call it from any page like this:
this.$root.$emit("component1");
If you're using Vue 3 with <script setup> sugar, note that internal bindings of a component are closed (not visible from outside the component) and you must use defineExpose(see docs) to make them visible from outside. Something like this:
<script setup lang="ts">
const method1 = () => { ... };
const method2 = () => { ... };
defineExpose({
method1,
method2,
});
</script>
Since
Components using are closed by default
Sometimes you want to keep these things contained within your component. Depending on DOM state (the elements you're listening on must exist in DOM when your Vue component is instantiated), you can listen to events on elements outside of your component from within your Vue component. Let's say there is an element outside of your component, and when the user clicks it, you want your component to respond.
In html you have:
Launch the component
...
<my-component></my-component>
In your Vue component:
methods() {
doSomething() {
// do something
}
},
created() {
document.getElementById('outsideLink').addEventListener('click', evt =>
{
this.doSomething();
});
}
I have used a very simple solution. I have included a HTML element, that calls the method, in my Vue Component that I select, using Vanilla JS, and I trigger click!
In the Vue Component, I have included something like the following:
<span data-id="btnReload" #click="fetchTaskList()"><i class="fa fa-refresh"></i></span>
That I use using Vanilla JS:
const btnReload = document.querySelector('[data-id="btnReload"]');
btnReload.click();
Trying to learn vuejs I got to the question how to pass any data from one component to all, using $emit but without using any #click.
It is possible some how that the data to be just available and grab it any time, without using the click?
Let's say we have this example with normal #click and $emit.
main.js
export const eventBus = new Vue()
Hello.vue
<template>
<div>
<h2>This is Hello component</h2>
<button
#click="emitGlobalClickEvent()">Click me</button>
</div>
</template>
<script>
import { eventBus } from '../main'
export default {
data () {
return {
msg: 'Welcome to Your Vue.js App'
}
},
methods: {
emitGlobalClickEvent () {
eventBus.$emit('messageSelected', this.msg)
}
}
}
</script>
User.vue
<template>
<div>
<h2>This is User component</h2>
<user-one></user-one>
</div>
</template>
<script>
import { eventBus } from '../main'
import UserOne from './UserOne.vue'
export default {
created () {
eventBus.$on('messageSelected', msg => {
console.log(msg)
})
},
components: {
UserOne
}
}
</script>
UserOne.vue
<template>
<div>
<h3>We are in UserOne component</h3>
</div>
</template>
<script>
import { eventBus } from '../main'
export default {
created () {
eventBus.$on('messageSelected', msg => {
console.log('From UserOne message !!!')
})
}
}
</script>
I want to get this message : Welcome to Your Vue.js App from Hello.vue in all components, but without #click, if is possible.
You can create another Javascript file which holds an Object with your initial state. Similar to how you define data in your components.
In this file your export your Object and import it in all Components which need access to this shared state. Something along the lines of this:
import Store from 'store';
data() {
return {
store
}
}
This might help:
https://v2.vuejs.org/v2/guide/state-management.html
At this point if you app grows even more in complexity you might also start checking out Vuex which helps to keep track of changes(mutations) inside of your store.
The given example is essential a very oversimplified version of Vuex.