When you inspect a Vue component that you have imported, you will get something like this:
import ClickB from 'ClickB.vue';
console.log(ClickB);
I have seen that nuxt adds a custom property there (called _nuxt), just like there is _ssrRegister. I have 2 questions:
How is it possible to add properties to the component?
Can you pass that property from the component to its instances?
It is simple. Just decorate Vue prototype like this to add instance method:
import Vue from 'vue';
// Adding an instance method
Vue.prototype.$someMethod = function (methodOptions) {
// Your own logic...
}
As a good practice, this code should be in your index.js or main.js file. Taking it one step further, you should put this code inside plugins as explained in Vue documentation for plugins.
You can always just add them to your definition and to access them you would use $options instance property.
Ref: https://v2.vuejs.org/v2/api/#vm-options
Related
I'm using Vue3 with the composition API. In a form-component I put ref's on each field (child-component).
For some reason the ref's of the custom components are different from ref's for Quasar components.
When I console.log a ref to a custom component I get this in DevTools:
Proxy {__v_skip: true}
(without any properties in Target)
while a ref to a Quasar components gives this :
Proxy {…}
(with all properties of the component in Target)
For this reason I can't use the ref to access properties or methods of these child components.
I have no idea what __v_skip even means.
My custom components are defined with script setup, could that be a reason?
Any idea how to fix this?
UPDATE
If I use defineExpose in the child components for the properties and methods I want to access from outside with a ref, it does work. Not really handy though, since these components have lots of props.
Seem likes currently you cannot access the custom component by ref, if your component is written by Composition API (<script setup>). But you can try the way I mention underneath.
In the Vue 3 doc, there are some lines mentioned this behavior:
An exception here is that components using <script setup> are private
by default: a parent component referencing a child component using
<script setup> won't be able to access anything unless the child
component chooses to expose a public interface using the defineExpose
macro
Read more here: Vue 3 - Ref on Component
That means if you want to access anything from the custom component, your component has to expose that information. I think it's because in Vue 3 you don't need to have root component anymore, so if you define a ref, Vue does not know what the component you want to ref to.
But...
You can try to use yourRef.value.$el, maybe it will help.
Example:
// Parent.vue
<template>
<Child ref="childRef">
</template>
<script setup lang="ts">
// Import things...
const childRef = ref<InstanceType<typeof Child> | null>(null);
onMounted(() => {
console.log(childRef.value.$el);
});
</script>
Hi in project i have included element-ui.
In app.js:
import Element from 'element-ui'
and after:
Vue.use(Element, {locale})
So in my single file components template i can use carousel like this: (In this component is not any initialization carousel via vue like import, parent whatever...)
<el-carousel>
<el-carousel-item>
<p>hello!</p>
</el-carousel-item>
</el-carousel>
And it works... BUT. How i can access to this element? Look to actual slide, use events and so on....?
I was tried in component something like:
import { Carousel } from 'element-ui';
and add to components list... It works, but it is another instance of this class...
So how i can GET real instance of carousel from DOM?
Easy. Make reference on element via ref attribute like this:
<el-carousel ref="myreference"></el-carousel>
and after this access:
console.log(this.$refs.myreference);
Following this tutorial, I'm trying to programmatically create instances of a component on my page.
The main snippet is this:
import Button from 'Button.vue'
import Vue from 'vue'
var ComponentClass = Vue.extend(Button)
var instance = new ComponentClass()
instance.$mount()
this.$refs.container.appendChild(instance.$el)
However I get two errors:
The component I'm trying to instantiate contains references to the store, and these don't work: "TypeError: Cannot read property 'state' of undefined".
For the last line of the snippet (this.$refs.container.appendChild(instance.$el)) I get this error: "Uncaught TypeError: Cannot read property 'container' of undefined"
I'm really not sure how to troubleshoot this, if anyone strong in Vue.js could give me some hint as to why I'm getting these errors and to solve them that would be terrific.
1) Since you're manually instantiating that component and it doesn't belong to your main app's component tree, the store won't be automatically injected into it from your root component. You'll have to manually provide the store to the constructor when you instantiate the component ..
import ProjectRow from "./ProjectRow.vue";
import Vue from "vue";
import store from "../store";
let ProjectRowClass = Vue.extend(ProjectRow);
let ProjectRowInstance = new ProjectRowClass({ store });
2) In a Vue Single File Component (SFC), outside of the default export this doesn't refer to the Vue instance, so you don't have access to $refs or any other Vue instance property/method. To gain access to the Vue instance you'll need to move this line this.$refs.container.appendChild(instance.$el) somewhere inside the default export, for example in the mounted hook or inside one of your methods.
See this CodeSandbox for an example of how you may go about this.
This is another way to instantiate a component in Vue.js, you can use two different root elements.
// Instantiate you main app
var app = new Vue({
el: '#app',
data: {
message: 'Hello Vue!'
}
})
//
// Then instantiate your component dynamically
//
// Create a component or import it.
const Hello = {
props: ['text'],
template: '<div class="hello">{{ text }}</div>',
};
// Create a componentClass by Vue.
const HelloCtor = Vue.extend(Hello);
// Use componentClass to instantiate your component.
const vm = new HelloCtor({
propsData: {
text: 'HI :)'
}
})
// then mount it to an element.
.$mount('#mount');
It works by assigning "this" to the property "parent". By setting the parent you also have access to the $store in the new instance. (Provided that "this" is another Vue instance/Component and already has access to the store, of course)
new (Vue.extend(YourNewComponent))({
parent: this,
propsData: {
whatever: 'some value',
},
}).$mount(el.querySelector('.some-id'))
If you don't need the reference to the parent, you can just leave "parent: this," out.
Important note: When mounting many (like 500+) items on the page this way you will get a huge performance hit. It is better to only give the new Component the necessary stuff via props instead of giving it the entire "this" object.
I went down this path, following all the examples above, and even this one: https://css-tricks.com/creating-vue-js-component-instances-programmatically/
While I got far, and it works (I made a lot of components this way), at least for my case, it came with drawbacks. For example I'm using Vuetify at the same time, and the dynamically added components didn't belong to the outer form, which meant that while local (per component) validation worked, the form didn't receive the overall status. Another thing that did not work was to disable the form. With more work, passing the form as parent property, some of that got working, but what about removing components. That didn't go well. While they were invisible, they were not really removed (memory leak).
So I changed to use render functions. It is actually much easier, well documented (both Vue 2 and Vue 3), and everything just works. I also had good help from this project: https://koumoul-dev.github.io/vuetify-jsonschema-form/latest/
Basically, to add a function dynamically, just implement the render() function instead of using a template. Works a bit like React. You can implement any logic in here to choose the tag, the options, everything. Just return that, and Vue will build the shadow-DOM and keep the real DOM up to date.
The methods in here seems to manipulate the DOM directly, which I'm glad I no longer have to do.
Hello I have this problem with vuejs and mixin.
I have a component that has 2 Mixin:
export default {
...
mixins:[Mixin1, Mixin2],
..
}
Both Mixins have a function named "delete", so If in my component I have a method like:
methods:{
deleteObj(){
this.delete()
}
}
I don't know which one function I call.
I know the simplest way is call with a different name the functions but is there a way to specify wich mixin to use?
If you duplicated definitions in methods in mixins, the last mixin will override the previous definitions. In your case this.delete() must called from Mixin2.
But if have lifecycle hooks like mounted, created ... those will be executed one by one in vuejs. There are some strategies followed for merging, vuejs itself you can found more at https://v2.vuejs.org/v2/guide/mixins.html
I got div with if.bind working as was suggested in this question: Using literal JavaScript values in an Aurelia view. But then I noticed that showTemplate on viewModel is being constantly checked by framework, about 10 times per second. The stack is following:
execute._prototypeProperties.visible.get (welcome.js:29)
getValue (dirty-checking.js:93)
isDirty (dirty-checking.js:127)
check (dirty-checking.js:63)
(anonymous function) (dirty-checking.js:49)
Is it supposed to be like this? Seems to be not very resource-friendly.
Best regards, Eugene.
Aurelia uses Object.observe for simple Javascript properties. If showTemplate is a function or a getter/setter, then Aurelia currently reverts to dirty checking. This can be removed by declaring the dependencies of the function. This is outlined here: https://github.com/aurelia/binding/pull/41
I have created a version of the Aurelia Skeleton project that implements this: https://github.com/ashleygrant/skeleton-navigation/tree/declare_dependencies
To implement this, you must switch to using the aurelia-main attribute. Add a main.js file:
import {LogManager} from 'aurelia-framework';
import {ConsoleAppender} from 'aurelia-logging-console';
import {ComputedObservationAdapter, ObjectObservationAdapter} from 'aurelia-framework';
LogManager.addAppender(new ConsoleAppender());
LogManager.setLevel(LogManager.levels.debug);
export function configure(aurelia) {
aurelia.use
.defaultBindingLanguage()
.defaultResources()
.router()
.eventAggregator();
aurelia.container
.registerSingleton(ObjectObservationAdapter, ComputedObservationAdapter);
aurelia.start().then(a => a.setRoot('app', document.body));
}
Then, in welcome.js, add the following import statement:
import {declarePropertyDependencies} from 'aurelia-framework';
and then outside the Welcome class, add the following method call:
declarePropertyDependencies(Welcome, 'fullName', ['firstName', 'lastName']);