Develop Reference

Vue slot not working - child elements show as empty array

I have the following code where I am trying to pass individual tab components into a tabs component via slots. However, the tabs do not seem to be getting passed. Putting {{ tabs }} on the template only shows an empty array.
<template>
<article>
{{ tabs }} // empty array
<header class="tabs">
<ul>
<li v-for="(tab, index) in tabs" :key="index">
<div class="nav-item"
:class="{ 'is-active': tab.isActive }"
#click="selectTab(tab)">
{{ tab.name }}
</div>
</li>
</ul>
</header>
<section class="tabs-details">
<slot></slot>
</section>
</article>
</template>
<script>
export default {
data: () => {
return {
tabs: []
}
},
methods: {
selectTab(selectedTab) {
this.tabs.forEach(tab => {
tab.isActive = tab.name === selectedTab.name;
});
}
},
created() {
console.log('created[Tabs.vue]-> ', this.$children) // nothing here
this.tabs = this.$children; // not working
}
}
</script>
I have my components registered in the parent like so:
import Tab from '#/components/Tab'
import Tabs from '#/components/Tabs'
export default {
components: {
Datepicker,
Tab,
Tabs
},
...
The template is pretty straight forward. Note, the contents of the individual tabs display fine when selected="true"
<Tabs>
<Tab name="hours" selected="true">Contents here...</Tab>
<Tab name="pay"></Tab>
</Tabs>
I have checked in the browser console and, although the nav-item <li> elements are being created, they have no content.
I'm new to slots so maybe I am missing something obvious or the code syntax I am using is outdated. Any help is much appreciated.

Try to use this.$slots :
this.tabs = this.$slots.default();//returns vnodes, that can be rendered via render function

$children has been deprecated in Vue 3:
In 3.x, the $children property is removed and no longer supported. Instead, if you need to access a child component instance, we recommend using template refs.
If you're trying to get children of <slot></slot>, use this.$slots.default(), as suggested in Boussadjra's answer.
In Vue2, the syntax for getting the default slot contents is this.$slots.default (not a function).
Notes:
you'll get back an array of VNodes, not actual DOM,
you can only access $slots after component has been mounted (e.g: in mounted() hook)
If you want specific data from the vNodes, you'll have to log them and see where exactly it is in your version of Vue (vNodes have had minor changes over time - they're considered internal API).
My advice would be to upgrade to a newer version of 2. If not 2.7.10, at least 2.6.14. Some of the available documentation on Vue 2 describes features which were not yet added in 2.2.3. $slots had a major revamp in 2.6.
For example, I was using slots at the time, but if you ask me now how they looked like, I couldn't tell you with certainty.

Vue3 Manually Render Slot Content

I'm trying to parse out the contents of a slot and render the contents in multiple places. The idea is to create a wizard that allows each step to be contained in a single component. Something like this:
Wizard Component Definition:
<ul>
<li v-for="icon in icons">{{icon}}<li>
</ul>
<section>
<ul>
<li v-for="body in bodies">{{body}}</li>
</ul>
</section>
Wizard Component Script
import {ref} from "vue";
export default {
setup(props, {slots}) {
const icons = ref([]);
const bodies = ref([]);
for (let item of slots.default()) {
// not sure if I need to call these, ex: item.children.icon()
icons.value.push(item.children.icon);
bodies.value.push(item.children.body);
}
return {icons, bodies};
}
}
Wizard Component Usage:
<wizard>
<wizard-page>
<template #icon>someIcon</template>
<template #body>someBody</template>
</wizard-page>
<wizard-page>
<template #icon>someIcon2</template>
<template #body>someBody2</template>
</wizard-page>
</wizard>
The obvious problem here is that everything is VNodes and doesn't just render nicely to the DOM. I've tried using render() and h() but those don't seem to be what I'm looking for. Also tried the v-html binding, but again, that isn't expecting a VNode.
I'm not sure if there's a better way to do this, or if I'm missing something simple here, but I'm not seeing an easy way to split apart a slot and render the contents in different places.

VUE 3
<component :is="body">
You can implement it in the following way
<ul>
<li v-for="body in bodies" :key="uniquekey">
<component :is="body" />
</li>
</ul>
link to docs:
https://vuejs.org/guide/essentials/component-basics.html#dynamic-components

Vuejs component click event not working

I am using Vuejs - Vuikit components and have the following setup:
<template>
<div class="uk-scope">
<vk-modal :show="isShow" v-if="config">
<vk-modal-close #click="alert('hello!')" large></vk-modal-close>
<vk-notification :messages.sync="messages"></vk-notification>
<app-breadcrumb :current-view="currentView" />
<!-- render the currently active component/page here -->
<component v-bind:is="currentView"/>
</vk-modal>
</div>
</template>
My issue is that, the close modal does not see to fire the #click function.
The parent component, does emit an event, but I would prefer to fire something directly from the close button.
I have tried to use #click.native="someFunction()", but this has not helped!

Hey I've not used vuikit before but from their documents they show this is how to close a modal. I would also remove that v-if="config" as that might be confusing Vue
<template>
<div class="uk-scope">
<vk-modal :show.sync="isShow">
<vk-modal-close #click="isShow = false" large></vk-modal-close>
<vk-notification :messages.sync="messages"></vk-notification>
<app-breadcrumb :current-view="currentView" />
<!-- render the currently active component/page here -->
<component v-bind:is="currentView"/>
</vk-modal>
</div>
</template>

Have you tried using #click.native="someFunction" note that this does not have ().

Vue js error: Component template should contain exactly one root element

I don't know what the error is, so far I am testing through console log to check for changes after selecting a file (for uploading).
When I run $ npm run watch, i get the following error:
"Webpack is watching the files…
95% emitting
ERROR Failed to compile with 1 errors
19:42:29
error in ./resources/assets/js/components/File.vue
(Emitted value instead of an instance of Error) Vue template syntax
error:
Component template should contain exactly one root element. If you
are using v-if on multiple elements, use v-else-if to chain them
instead.
# ./resources/assets/js/components/AvatarUpload.vue 5:2-181 #
./resources/assets/js/app.js # multi ./resources/assets/js/app.js
./resources/assets/sass/app.scss"
My File.vue is
<template>
<div class="form-group">
<label for="avatar" class="control-label">Avatar</label>
<input type="file" v-on:change="fileChange" id="avatar">
<div class="help-block">
Help block here updated 4 🍸 ...
</div>
</div>
<div class="col-md-6">
<input type="hidden" name="avatar_id">
<img class="avatar" title="Current avatar">
</div>
</template>
<script>
export default{
methods: {
fileChange(){
console.log('Test of file input change')
}
}
}
</script>
Any ideas on how to solve this? What is actually the error?

Note This answer only applies to version 2.x of Vue. Version 3 has lifted this restriction.
You have two root elements in your template.
<div class="form-group">
...
</div>
<div class="col-md-6">
...
</div>
And you need one.
<div>
<div class="form-group">
...
</div>
<div class="col-md-6">
...
</div>
</div>
Essentially in Vue you must have only one root element in your templates.

For a more complete answer: http://www.compulsivecoders.com/tech/vuejs-component-template-should-contain-exactly-one-root-element/
But basically:
Currently, a VueJS template can contain only one root element (because of rendering issue)
In cases you really need to have two root elements because HTML structure does not allow you to create a wrapping parent element, you can use vue-fragment.
To install it:
npm install vue-fragment
To use it:
import Fragment from 'vue-fragment';
Vue.use(Fragment.Plugin);
// or
import { Plugin } from 'vue-fragment';
Vue.use(Plugin);
Then, in your component:
<template>
<fragment>
<tr class="hola">
...
</tr>
<tr class="hello">
...
</tr>
</fragment>
</template>

You need to wrap all the html into one single element.
<template>
<div>
<div class="form-group">
<label for="avatar" class="control-label">Avatar</label>
<input type="file" v-on:change="fileChange" id="avatar">
<div class="help-block">
Help block here updated 4 🍸 ...
</div>
</div>
<div class="col-md-6">
<input type="hidden" name="avatar_id">
<img class="avatar" title="Current avatar">
</div>
</div>
</template>
<script>
export default{
methods: {
fileChange(){
console.log('Test of file input change')
}
}
}
</script>

if, for any reasons, you don't want to add a wrapper (in my first case it was for <tr/> components), you can use a functionnal component.
Instead of having a single components/MyCompo.vue you will have few files in a components/MyCompo folder :
components/MyCompo/index.js
components/MyCompo/File.vue
components/MyCompo/Avatar.vue
With this structure, the way you call your component won't change.
components/MyCompo/index.js file content :
import File from './File';
import Avatar from './Avatar';
const commonSort=(a,b)=>b-a;
export default {
functional: true,
name: 'MyCompo',
props: [ 'someProp', 'plopProp' ],
render(createElement, context) {
return [
createElement( File, { props: Object.assign({light: true, sort: commonSort},context.props) } ),
createElement( Avatar, { props: Object.assign({light: false, sort: commonSort},context.props) } )
];
}
};
And if you have some function or data used in both templates, passed them as properties and that's it !
I let you imagine building list of components and so much features with this pattern.

Component template should contain exactly one root element. If you are using v-if on multiple elements, use v-else-if to chain them instead.
The right approach is
<template>
<div> <!-- The root -->
<p></p>
<p></p>
</div>
</template>
The wrong approach
<template> <!-- No root Element -->
<p></p>
<p></p>
</template>
Multi Root Components
The way around to that problem is using functional components, they are components where you have to pass no reactive data means component will not be watching for any data changes as well as not updating it self when something in parent component changes.
As this is a work around it comes with a price, functional components don't have any life cycle hooks passed to it, they are instance less as well you cannot refer to this anymore and everything is passed with context.
Here is how you can create a simple functional component.
Vue.component('my-component', {
// you must set functional as true
functional: true,
// Props are optional
props: {
// ...
},
// To compensate for the lack of an instance,
// we are now provided a 2nd context argument.
render: function (createElement, context) {
// ...
}
})
Now that we have covered functional components in some detail lets cover how to create multi root components, for that I am gonna present you with a generic example.
<template>
<ul>
<NavBarRoutes :routes="persistentNavRoutes"/>
<NavBarRoutes v-if="loggedIn" :routes="loggedInNavRoutes" />
<NavBarRoutes v-else :routes="loggedOutNavRoutes" />
</ul>
</template>
Now if we take a look at NavBarRoutes template
<template>
<li
v-for="route in routes"
:key="route.name"
>
<router-link :to="route">
{{ route.title }}
</router-link>
</li>
</template>
We cant do some thing like this we will be violating single root component restriction
Solution
Make this component functional and use render
{
functional: true,
render(h, { props }) {
return props.routes.map(route =>
<li key={route.name}>
<router-link to={route}>
{route.title}
</router-link>
</li>
)
}
Here you have it you have created a multi root component, Happy coding
Reference for more details visit: https://blog.carbonteq.com/vuejs-create-multi-root-components/

In addition to Bert and blobmaster responses:
If you need to remove the root element from the DOM you can exploit css and use display: value on the root element.

Bit of a misleading error.
What fixed it on my side was the fact that I had an additional </div> without an opening <div>.
I spotted it using Find/Replace on "div" which gave an odd number.

Wrap everything in one div and it will resolve the issue.
For example,
div
----div
----/div>
----div>
----/div>
/div
It is similar concept to React.js

For vue 3 they removed this constraint in template syntax :
<template>
<header>...</header>
<main v-bind="$attrs">...</main>
<footer>...</footer>
</template>
but it's still existing in JSX syntax :
Incorrect ❌
setup(props,{attrs}) {
return ()=>(
<header>...</header>
<main {..attrs}>...</main>
<footer>...</footer>
)
}
Correct ✔
setup(props,{attrs}) {
return ()=>(
<>
<header>...</header>
<main {..attrs}>...</main>
<footer>...</footer>
</>
)
}

I experienced this kind of issue and the issue was fixed by adding a main parent div tag or section if it is a section type of component.
<div class="list-of-friends">
<h3>Hello World</h3>
</div>

I was confused as I knew VueJS should only contain 1 root element and yet I was still getting this same "template syntax error Component template should contain exactly one root element..." error on an extremely simple component. Turns out I had just mispelled </template> as </tempate> and that was giving me this same error in a few files I copied and pasted. In summary, check your syntax for any mispellings in your component.

instead of using this
Vue.component('tabs', {
template: `
<div class="tabs">
<ul>
<li class="is-active"><a>Pictures</a></li>
<li><a>Music</a></li>
<li><a>Videos</a></li>
<li><a>Documents</a></li>
</ul>
</div>
<div class="tabs-content">
<slot></slot>
</div>
`,
});
you should use
Vue.component('tabs', {
template: `
<div>
<div class="tabs">
<ul>
<li class="is-active"><a>Pictures</a></li>
<li><a>Music</a></li>
<li><a>Videos</a></li>
<li><a>Documents</a></li>
</ul>
</div>
<div class="tabs-content">
<slot></slot>
</div>
</div>
`,
});

Just make sure that you have one root div and put everything inside this root
<div class="root">
<!--and put all child here --!>
<div class='child1'></div>
<div class='child2'></div>
</div>
and so on

Nested vue.js instances/elements

This may sound like a real noob question, but I'm pretty new to MVVM... or even MVC in JS, so sorry in advance.
I'm playing about with vue.js, and loving the simplicity of it so far. But for what I am trying to do, I think I need to go about it a different way.
I want to nest Vue instances/elements inside each other, but of course, the parent will then use the child when it reads through the DOM on init.
For the sake of arguments, below is an example of what I mean, I am not doing anything like this, but this is the simplest way to example what I mean:
<body>
{{ message }}
<div id="another">
{{ message }}
</div>
</body>
Then my JS for example would be:
new Vue({
el: "body",
data: {
message: "I'm the parent"
}
});
new Vue({
el: "#another",
data: {
message: "I'm the child"
}
});
The outcome would be:
<body>
I'm the parent
<div id="another">
I'm the parent
</div>
</body>
Now I completely understand why it is doing this and in fact, it should do this, but my example is just trying to illustrate how I would do something like this?
In my real life project, I have a v-class on my body that changes when stuff happens in the body (in numerous places) but of course my body will also want other instances of vue that do other stuff.
how would I go about nesting? Is there feature in vue to deal with this? Do I need to deal with components? Or maybe, fetch the body from within a child element (e.g. like jQuery would with $("body")) then manipulate it within the Vue instance?
Hope this question isn't too stupid and someone can point me in the right direction.
Thanks

Think components.
http://vuejs.org/guide/components.html
Create a Vue instance on the body as you have above, but anything nested in that is a component. Pass data via props.

Passing in data via props is only one way to do it. Nesting components and inheriting from the parent works fine as well.
Example: http://jsfiddle.net/hajkrupo/3/
<encapsulated-component inline-template>
<header>
<cart-status></cart-status>
</header>
<cart></cart>
</encapsulated-component>

You can do this with <slot> tags. Here is an example.
1.So, first, you need to do is creating a basic layout component, like this.
You need to add <slot> tag whereever you want. Very important think is the name attribute on <slot> tag.
var basicLayout = Vue.component("basic-layout", {
template: `
<div class="basic-layout">
<header>
<slot name="header"></slot>
</header>
<main>
<slot></slot>
</main>
<footer>
<slot name="footer"></slot>
</footer>
</div>
`
});
2.Then create your custom component. I created myHeader component to show you, how it works.
var myHeader = Vue.component("my-header", {
template: `
<div class="header">
<ul>
<li>HOME</li>
<li>ABOUT</li>
<li>CONTACT</li>
</ul>
</div>
`
});
3.Put this sample code in your HTML file.
To put some content in current slot, just use the slot attribute in your component or your tag.
<div class="app">
<basic-layout>
<my-header slot="header"></my-header>
<p>Content in <main> tag</p>
<p slot="footer">Content in footer</p>
</basic-layout>
</div>
4.The result will be like this:
<div class="app">
<div class="basic-layout">
<header>
<div class="header">
<ul>
<li>HOME</li>
<li>ABOUT</li>
<li>CONTACT</li>
</ul>
</div>
</header>
<main>
<p>Content in <main> tag</p>
<main>
<footer>
<p>Content in footer</p>
</footer>
</div>
</div>
Please, see the documentation in official page of Vue.js
Just click link here for more info.
Here is example in jsfiddle