I have a sample project at https://github.com/eric-g-97477-vue/vue-project
This is a default vue project with vueuse installed.
I modified the script and template part of HelloWorld.vue to be:
<script setup>
import { watch, ref } from "vue";
import { useElementVisibility } from "#vueuse/core";
defineProps({
msg: {
type: String,
required: true,
},
});
const me = ref(null);
const isVisible = useElementVisibility(me);
watch(me, (newValue, oldValue) => {
console.log("visibilityUpdated", newValue, oldValue);
});
</script>
<template>
<div ref="me" class="greetings">
<h1 class="green">{{ msg }}</h1>
<h3>
You’ve successfully created a project with
Vite +
Vue 3.
</h3>
</div>
</template>
and adjusted App.vue so the HelloWorld component could be easily scrolled on or off the screen.
This appears to match the Usage demo code. The primary difference being that I am using <script setup> and the demo code is not. But, perhaps, I need to do things differently as a result...?
The watcher will fire when the app loads and indicates that the HelloWorld component is visible, but it is not. Additionally, regardless if I scroll so the component is visible or not, the watcher does not fire again.
What am I doing wrong?
UPDATE: modified the question based on the discovery that I needed to add ref="me" to the div in the template. Without this, the watcher was never firing.
Related
I'm a beginner regarding Vite/Vue3 and currently I am facing an issue where I need the combined knowledge of the community.
I've created a Vite/Vue3 app and installed TailwindCSS to it:
npm create vite#latest my-vite-vue-app -- --template vue
cd my-vite-vue-app
npm install -D tailwindcss postcss autoprefixer
npx tailwindcss init -p
Then I followed the instructions on Tailwind's homepage:
Add the paths to all of your template files in your tailwind.config.js file.
Import the newly-created ./src/index.css file in your ./src/main.js file. Create a ./src/index.css file and add the #tailwind directives for each of Tailwind’s layers.
Now I have a working Vite/Vue3/TailwindCSS app and want to add the feature to toggle dark mode to it.
The Tailwind documentation says this can be archived by adding darkMode: 'class' to tailwind.config.js and then toggle the class dark for the <html> tag.
I made this work by using this code:
Inside index.html
<html lang="en" id="html-root">
(...)
<body class="antialiased text-slate-500 dark:text-slate-400 bg-white dark:bg-slate-900">
<div id="app"></div>
<script type="module" src="/src/main.js"></script>
</body>
</html>
Inside About.vue
<template>
<div>
<h1>This is an about page</h1>
<button #click="toggleDarkMode">Toggle</botton>
</div>
</template>
<script>
export default {
methods: {
toggleDarkMode() {
const element = document.getElementById('html-root')
if (element.classList.contains('dark')) {
element.classList.remove('dark')
} else {
element.classList.add('dark')
}
},
},
};
</script>
Yes, I know that this isn't Vue3-style code. And, yes, I know that one could do element.classList.toggle() instead of .remove() and .add(). But maybe some other beginners like me will look at this in the future and will be grateful for some low-sophisticated code to start with. So please have mercy...
Now I'll finally come to the question I want to ask the community:
I know that manipulating the DOM like this is not the Vue-way of doing things. And, of course, I want to archive my goal the correct way. But how do I do this?
Believe me I googled quite a few hours but I didn't find a solution that's working without installing this and this and this additional npm module.
But I want to have a minimalist approach. As few dependancies as possbile in order not to overwhelm me and others that want to start learning.
Having that as a background - do you guys and gals have a solution for me and other newbies? :-)
The target element of your event is outside of your application. This means there is no other way to interact with it other than by querying it via the DOM available methods.
In other words, you're doing it right.
If the element was within the application, than you'd simply link class to your property and let Vue handle the specifics of DOM manipulation:
:class="{ dark: darkMode }"
But it's not.
As a side note, it is really important your toggle method doesn't rely on whether the <body> element has the class or not, in order to decide if it should be applied/removed. You should keep the value saved in your app's state and that should be your only source of truth.
That's the Vue principle you don't want break: let data drive the DOM state, not the other way around.
It's ok to get the value (on mount) from current state of <body>, but from that point on, changes to your app's state will determine whether or not the class is present on the element.
vue2 example:
Vue.config.devtools = false;
Vue.config.productionTip = false;
new Vue({
el: '#app',
data: () => ({
darkMode: document.body.classList.contains('dark')
}),
methods: {
applyDarkMode() {
document.body.classList[
this.darkMode ? 'add' : 'remove'
]('dark')
}
},
watch: {
darkMode: 'applyDarkMode'
}
})
body.dark {
background-color: #191919;
color: white;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.6.14/vue.js"></script>
<div id="app">
<label>
<input type="checkbox" v-model="darkMode">
dark mode
</label>
</div>
vue3 example:
const {
createApp,
ref,
watchEffect
} = Vue;
createApp({
setup() {
const darkMode = ref(document.body.classList.contains('dark'));
const applyDarkMode = () => document.body.classList[
darkMode.value ? 'add' : 'remove'
]('dark');
watchEffect(applyDarkMode);
return { darkMode };
}
}).mount('#app')
body.dark {
background-color: #191919;
color: white;
}
<script src="https://unpkg.com/vue#next/dist/vue.global.prod.js"></script>
<div id="app">
<label>
<input type="checkbox" v-model="darkMode">
dark mode
</label>
</div>
Obviously, you might want to keep the state of darkMode in some external store, not locally, in data (and provide it in your component via computed), if you use it in more than one component.
What you're looking for is Binding Classes, but where you're getting stuck is trying to manipulate the <body> which is outside of the <div> your main Vue instance is mounted in.
Now your problem is your button is probably in a different file to your root <div id="app"> which starts in your App.vue from boilerplate code. Your two solutions are looking into state management (better for scalability), or doing some simple variable passing between parents and children. I'll show the latter:
Start with your switch component:
// DarkButton.vue
<template>
<div>
<h1>This is an about page</h1>
<button #click="toggleDarkMode">Toggle</button>
</div>
</template>
<script>
export default {
methods: {
toggleDarkMode() {
this.$emit('dark-switch');
},
},
};
</script>
This uses component events ($emit)
Then your parent/root App.vue will listen to that toggle event and update its class in a Vue way:
<template>
<div id="app" :class="{ dark: darkmode }">
<p>Darkmode: {{ darkmode }}</p>
<DarkButton #dark-switch="onDarkSwitch" />
</div>
</template>
<script>
import DarkButton from './components/DarkButton.vue';
export default {
name: 'App',
components: {
DarkButton,
},
data: () => ({
darkmode: false,
}),
methods: {
onDarkSwitch() {
this.darkmode = !this.darkmode;
},
},
};
</script>
While tailwind say for Vanilla JS to add it into your <body>, you generally shouldn't manipulate that from that point on. Instead, don't manipulate your <body>, only go as high as your <div id="app"> with things you want to be within reach of Vue.
I have a paginated component. The async setup() method is pulling data from an API to populate the page. It works fine when the route is directly loaded, but when I change the route to a different page slug (eg. clicking a router-link), the component is not reloaded and setup is not executed again to fetch the new data.
I guess I somehow want to force reloading the component?
This is my MainApp component it has the router view and fallback.
<router-view v-slot="{ Component }">
<Suspense>
<template #default>
<component :is="Component" />
</template>
<template #fallback>
loading...
</template>
</Suspense>
</router-view>
The router looks kinda like that. You see the page component takes a page_slug:
const routes: Array<RouteRecordRaw> = [
{
path: "/",
name: "",
component: MainApp,
children: [
{
name: "page",
path: "page/:page_slug",
component: Page,
props: true,
},
// [...]
]
}
And this is how my Page component looks like. It uses the page_slug to load data from an API which is then used in the template:
<template>
<div> {{ pageData }} </div>
</template>
export default defineComponent({
name: "Page",
props: {
page_slug: {
type: String,
required: true,
},
},
async setup(props) {
const pageData = await store.dispatch("getPageData", {
page_slug: props.page_slug
});
return { pageData }
}
}
When I directly open the route, the fallback "loading..." is nicely shown until the data is returned and the component is rendered.
But when I do a route change to another page, then async setup() is not executed again. In that case the url in the browser updates, but the data just remains the same.
How can I solve this case? Do I have to force reload the component somehow? Or have an entirely different architecture to the data loading?
The answer is simple, when trying to create Vue 3 Single File Components (SFCs) in Composition API way as shown below:
<template>
<!-- Your HTML code-->
</template>
<script>
export default {
name: 'ComponentName',
async setup():{
// Your code
}
};
</script>
<style>
/*Your Style Code*/
</style>
<script>, will only executes once when the component is first imported. So, when the data have changed by other component, the component above will not updated or in other words not re-created.
To make your component re-created whenever it about to mount, you have to use <script setup> which will make sure the code inside will execute every time an instance of the component is created, but you need to re-write your script code with few changes in comparison when using setup() method, and also you are able to use both of scripts like this:
<script>
// normal <script>, executed in module scope (only once)
runSideEffectOnce()
// declare additional options
export default {
name: "ComponentName",
inheritAttrs: false,
customOptions: {}
}
</script>
<script setup>
// executed in setup() scope (for each instance)
</script>
Read this documentation carefully to have full idea.
I am terribly new to Vue, so forgive me if my terminology is off. I have a .NET Core MVC project with small, separate vue pages. On my current page, I return a view from the controller that just has:
#model long;
<div id="faq-category" v-bind:faqCategoryId="#Model"></div>
#section Scripts {
<script src="~/scripts/js/faqCategory.js"></script>
}
Where I send in the id of the item this page will go grab and create the edit form for. faqCategory.js is the compiled vue app. I need to pass in the long parameter to the vue app on initialization, so it can go fetch the full object. I mount it with a main.ts like:
import { createApp } from 'vue'
import FaqCategoryPage from './FaqCategoryPage.vue'
createApp(FaqCategoryPage)
.mount('#faq-category');
How can I get my faqCategoryId into my vue app to kick off the initialization and load the object? My v-bind attempt seems to not work - I have a #Prop(Number) readonly faqCategoryId: number = 0; on the vue component, but it is always 0.
My FaqCategoryPAge.vue script is simply:
<script lang="ts">
import { Options, Vue } from "vue-class-component";
import { Prop } from 'vue-property-decorator'
import Card from "#/Card.vue";
import axios from "axios";
import FaqCategory from "../shared/FaqCategory";
#Options({
components: {
Card,
},
})
export default class FaqCategoryPage extends Vue {
#Prop(Number) readonly faqCategoryId: number = 0;
mounted() {
console.log(this.faqCategoryId);
}
}
</script>
It seems passing props to root instance vie attributes placed on element the app is mounting on is not supported
You can solve it using data- attributes easily
Vue 2
const mountEl = document.querySelector("#app");
new Vue({
propsData: { ...mountEl.dataset },
props: ["message"]
}).$mount("#app");
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app" data-message="Hello from HTML">
{{ message }}
</div>
Vue 3
const mountEl = document.querySelector("#app");
Vue.createApp({
props: ["message"]
}, { ...mountEl.dataset }).mount("#app");
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/3.0.0/vue.global.js"></script>
<div id="app" data-message="Hello from HTML">
{{ message }}
</div>
Biggest disadvantage of this is that everything taken from data- attributes is a string so if your component expects something else (Number, Boolean etc) you need to make conversion yourself.
One more option of course is pushing your component one level down. As long as you use v-bind (:counter), proper JS type is passed into the component:
Vue.createApp({
components: {
MyComponent: {
props: {
message: String,
counter: Number
},
template: '<div> {{ message }} (counter: {{ counter }}) </div>'
}
},
}).mount("#app");
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/3.0.0/vue.global.js"></script>
<div id="app">
<my-component :message="'Hello from HTML'" :counter="10" />
</div>
Just an idea (not a real problem)
Not really sure but it can be a problem with Props casing
HTML attribute names are case-insensitive, so browsers will interpret any uppercase characters as lowercase. That means when you're using in-DOM templates, camelCased prop names need to use their kebab-cased (hyphen-delimited) equivalents
Try to change your MVC view into this:
<div id="faq-category" v-bind:faq-category-id="#Model"></div>
Further to Michal Levý's answer regarding Vue 3, you can also implement that pattern with a Single File Component:
app.html
<div id="app" data-message="My Message"/>
app.js
import { createApp } from 'vue';
import MyComponent from './my-component.vue';
const mountEl = document.querySelector("#app");
Vue.createApp(MyComponent, { ...mountEl.dataset }).mount("#app");
my-component.vue
<template>
{{ message }}
</template>
<script>
export default {
props: {
message: String
}
};
</script>
Or you could even grab data from anywhere on the parent HTML page, eg:
app.html
<h1>My Message</h1>
<div id="app"/>
app.js
import { createApp } from 'vue';
import MyComponent from './my-component.vue';
const message = document.querySelector('h1').innerText;
Vue.createApp(MyComponent, { message }).mount("#app");
my-component.vue
<template>
{{ message }}
</template>
<script>
export default {
props: {
message: String
}
};
</script>
To answer TheStoryCoder's question: you would need to use a data prop. My answers above demonstrate how to pass a value from the parent DOM to the Vue app when it is mounted. If you wanted to then change the value of message after it was mounted, you would need to do something like this (I've called the data prop myMessage for clarity, but you could also just use the same prop name message):
<template>
{{ myMessage }}
<button #click="myMessage = 'foo'">Foo me</button>
</template>
<script>
export default {
props: {
message: String
},
data() {
return {
myMessage: this.message
}
}
};
</script>
So I'm not at all familiar with .NET and what model does, but Vue will treat the DOM element as a placeholder only and it does not extend to it the same functionality as the components within the app have.
so v-bind is not going to work, even without the value being reactive, the option is not there to do it.
you could try a hack to access the value and assign to a data such as...
const app = Vue.createApp({
data(){
return {
faqCategoryId: null
}
},
mounted() {
const props = ["faqCategoryId"]
const el = this.$el.parentElement;
props.forEach((key) => {
const val = el.getAttribute(key);
if(val !== null) this[key] = (val);
})
}
})
app.mount('#app')
<script src="https://unpkg.com/vue#3.0.0-rc.11/dist/vue.global.prod.js"></script>
<div id="app" faqCategoryId="12">
<h1>Faq Category Id: {{faqCategoryId}}</h1>
</div>
where you get the value from the html dom element, and assign to a data. The reason I'm suggesting data instead of props is that props are setup to be write only, so you wouldn't be able to override them, so instead I've used a variable props to define the props to look for in the dom element.
Another option
is to use inject/provide
it's easier to just use js to provide the variable, but assuming you want to use this in an mvc framework, so that it is managed through the view only. In addition, you can make it simpler by picking the exact attributes you want to pass to the application, but this provides a better "framework" for reuse.
const mount = ($el) => {
const app = Vue.createApp({
inject: {
faqCategoryId: {
default: 'optional'
},
},
})
const el = document.querySelector($el)
Object.keys(app._component.inject).forEach(key => {
if (el.getAttribute(key) !== null) {
app.provide(key, el.getAttribute(key))
}
})
app.mount('#app')
}
mount('#app')
<script src="https://unpkg.com/vue#3.0.0-rc.11/dist/vue.global.prod.js"></script>
<div id="app" faqCategoryId="66">
<h1>Faq Category Id: {{faqCategoryId}}</h1>
</div>
As i tried in the following example
https://codepen.io/boussadjra/pen/vYGvXvq
you could do :
mounted() {
console.log(this.$el.parentElement.getAttribute("faqCategoryId"));
}
All other answers might be valid, but for Vue 3 the simple way is here:
import {createApp} from 'vue'
import rootComponent from './app.vue'
let rootProps = {};
createApp(rootComponent, rootProps)
.mount('#somewhere')
I'm beginning with vuejs and I try to figure what could be done about reference of child component instance in root instance. I used ref attribute and it works pretty well, except if I use it in a single file component (in the template tags). In this specific case, I get 'undefined'.
So, I try to understand why, because it could be very useful for establishing dynamic references. I could probably bypass that situation easily, but I would like to understand the problem instead of run away.
So if someone have an idea ;)
I am using webpack to import my single file component in my app.js and compiled it. However the template compilation isn't done by webpack, but by the browser at runtime (maybe it's the beginning of an explanation ?).
My app is very simple, and I log my references on click on the header, so I don't think it's lifecylce callback related.
Here is my files :
app.js
import Vue from 'Vue';
import appButton from './appButton.vue';
import appSection from './appSection.vue';
var app = new Vue({
el: '#app',
components:
{
'app-button' : appButton
},
methods:
{
displayRefs: function()
{
console.log(this.$refs.ref1);
console.log(this.$refs.ref2);
console.log(this.$refs.ref3);
}
}
});
my component appButton.vue
<template>
<div ref="ref3" v-bind:id="'button-'+name" class="button">{{label}}</div>
</template>
<script>
module.exports =
{
props: ['name', 'label']
}
</script>
my index.html body
<body>
<div id="app">
<div id="background"></div>
<div id="foreground">
<img id="photo" src="./background.jpg"></img>
<header ref="ref1">
<h1 v-on:click="displayRefs">My header exemple</h1>
</header>
<nav>
<app-button ref="ref2" name="presentation" label="Qui sommes-nous ?"></app-button>
</nav>
</div>
</div>
<script src="./app.js"></script>
</body>
ref1 (header tag) and ref2 (app-button tag) are both found. But ref3 (in my single file component) is undefined. Also
Thanks for all the piece of answer you could give me, hoping it's not a silly mistake.
A ref you set is only accessible in the component itself.
If you try to console.log(this.$refs.ref3); into a method from appButton.vue, it will work. But it won't work in the parent.
If you want to access that ref from the parent, you need to use the $ref2 to access the component, and then use the $ref3. Try this:
var app = new Vue({
el: '#app',
components:
{
'app-button' : appButton
},
methods:
{
displayRefs: function()
{
console.log(this.$refs.ref1);
console.log(this.$refs.ref2);
console.log(this.$refs.ref2.$refs.ref3); // Here, ref3 will be defined.
}
}
});
Accessing some child ref from the parent is not supposed to be a good practice tho.
I have finally been able to test .vue components the way I want to, however, I'm a little confused by a couple of things I had to add in order to get it working - any explanations would be great. This is testing child components too.
Using the vueify-template 1.0, I altered the Hello.vue to be this
<template>
<div class="hello">
<h1>{{ msg }}</h1>
<child></child>
</div>
</template>
<script>
import Vue from 'vue'
import Child from './Child.vue'
export default Vue.extend({
data () {
return {
msg: 'Hello World!'
}
},
components: {
Child
}
})
</script>
Child looks like this:
<template>
<div class="child">
Child Content
</div>
</template>
<script>
import Vue from 'vue'
export default Vue.extend({
})
</script>
Now I can test these the way I want to with:
import Vue from 'vue'
import Hello from '../../src/components/Hello.vue'
describe('Hello.vue', () => {
it('should render correct contents into el', () => {
var mount = document.createElement('div');
const vm = new Hello({
el: mount,
});
expect(vm.$el.querySelector('.hello h1').textContent).toBe('Hello World!')
expect(vm.$el.querySelector('.hello .child').textContent.trim()).toBe('Child Content')
})
})
Now - a few questions if anyone has time to answer, I'm quite new to Vue & ES6 etc. so apologies if they're obvious!
I had to do the export default Vue.extend({ .... }) before I was able to mount the components in my test. Does this matter? The app seems to perform identically so I'm not really sure what's going on here.
The main gotcha was that in my <template> if I didn't have the correctly named wrapper div class (e.g. <div class="child">) then nothing would be generated into the vm.$el . Oddly (to me) if I have exactly the same test, but don't include the <child></child> tag, then the vm.$el will be at least created... so I'm somewhat confused.
Is this an evil way to test? Am I fighting the framework?
Thanks for any and all pointers - I hope this isn't too generic a question for SO.