Append child to $slot.default - vue.js

Question

I have a component that I need display some custom modal on screen. I don't know where I should put this dialog content, so I did something like that:
<template>
<div class="ComponentItself">
<div v-show="false" ref="ModalContent">
Hello!
</div>
<button v-on:click="showModal">Show modal</button>
</div>
</template>
[...]
Note: I could not set the tag name of [ref=ModalContent] to template because the vue reserves this tag to another feature.
My idea is when I click on "show modal" it open creates an instance of another component (v-dialog) that I have created with the [ref=ModalContent] content (it should be compiled to support nested vue components).
import Dialog from './Dialog';
const DialogCtor = Vue.extend(Dialog);
const dialog = new DialogCtor({ propsData: {...} });
dialog['$slots'].default = [ this.$refs['templateNewFolder'].innerHTML ];
{something like document.body.appendChild(dialog.$el)}
This another component have a slot that could receives the HTML content to be displayed inside of that. And it just not works. The modal is displayed, but the slot content is undefined or the HTML content not parsed.
<div class="Dialog">
[...]
<slot></slot>
[...]
</div>
The current result is something like:
What I need:
I need to know if I am on the right way. I have about the component feature, but I could not identify or understand if it is/could resolve my problem;
What I could do to make it work;
Some similar project could help it, but I could not found anyone;
Maybe I could resolve my problem if is possible I just .appendChild() directly to $slot.default, but it is not possible;

Answer 1

It seems to me this might be a case of an XY problem.
What probably happens is that you do not need to manually fill $slot.default, but use your Dialog component a more standard way. Since there is little detail about the latter in your question, that component might also need some refactoring to fit this "standard way".
So a more standard approach would be to directly use your <custom-dialog> component in the template of your parent, instead of using a placeholder (the one you reference as ModalContent) that you have to hide. That way, whatever HTML you pass within that <custom-dialog> will be fed into your Dialog's <slot> (designed beaviour of slot).
That way you also save the hassle of having to manually instantiate your Dialog component.
Then you can toggle your <custom-dialog> visibility (with v-if or v-show) or even manipulate its position in the DOM as you mention in your code; you can access its DOM node as $el: this.$refs.ModalContent.$el when ModalContent is a Vue instance.
You could also factorize the showModal method by delegating it to the Dialog component.
Code example:
Vue.component('modal-dialog', {
template: '#modal-dialog',
data() {
return {
modalShown: false,
};
},
methods: {
showModal() {
this.modalShown = true;
},
hideModal() {
this.modalShown = false;
},
},
});
new Vue({
el: '#app',
methods: {
showModal() {
this.$refs.ModalContent.showModal();
},
},
});
/*
https://sabe.io/tutorials/how-to-create-modal-popup-box
MIT License https://sabe.io/terms#Licensing
*/
.modal {
position: fixed;
left: 0;
top: 0;
width: 100%;
height: 100%;
background-color: rgba(0, 0, 0, 0.5);
opacity: 0;
visibility: hidden;
transform: scale(1.1);
transition: visibility 0s linear 0.25s, opacity 0.25s 0s, transform 0.25s;
}
.modal-content {
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
background-color: white;
padding: 1rem 1.5rem;
width: 24rem;
border-radius: 0.5rem;
}
.close-button {
float: right;
width: 1.5rem;
line-height: 1.5rem;
text-align: center;
cursor: pointer;
border-radius: 0.25rem;
background-color: lightgray;
}
.close-button:hover {
background-color: darkgray;
}
.show-modal {
opacity: 1;
visibility: visible;
transform: scale(1.0);
transition: visibility 0s linear 0s, opacity 0.25s 0s, transform 0.25s;
}
<script src="https://unpkg.com/vue/dist/vue.js"></script>
<div id="app">
<modal-dialog ref="ModalContent">
Hello!
</modal-dialog>
<h1>Hello World</h1>
<button v-on:click="showModal">Show modal</button>
</div>
<template id="modal-dialog">
<div class="modal" :class="{'show-modal': modalShown}" #click="hideModal">
<div class="modal-content">
<span class="close-button" ref="closeButton" #click="hideModal">×</span>
<slot></slot>
</div>
</div>
</template>
Now if you really want to fiddle with $slot, #Sphinx's linked answer in the question comments is an acceptable approach. Note that the accepted answer there also favours the standard usage. It seems to me this is also what #Sphinx implies in their 2nd comment.