listen to events from dynamic vue components - vue.js

Question

How would you listen to an event emitted by a dynamically created component instance?
In the example, the top component is added in the DOM, while the second is dynamically created in javascript.
Vue.component("button-counter", {
data: function() {
return {
count: this.initial_count
}
},
props: ['initial_count'],
methods: {
add: function() {
this.count++
this.$emit('myevent', this.count)
}
},
template: '<button v-on:click="add">You clicked me {{ count }} times.</button>'
})
let app = new Vue({
el: "#app",
data() {
return {
initial_count: 10,
}
},
mounted: function() {
let initial_count = this.initial_count
let ButtonCounterComponentClass = Vue.extend({
data: function() {
return {}
},
render(h) {
return h("button-counter", {
props: {
initial_count: initial_count
}
})
}
})
let button_counter_instance = new ButtonCounterComponentClass()
button_counter_instance.$mount()
button_counter_instance.$on('myevent', function(count) {
console.log('listened!')
this.say(count)
})
this.$refs.container.appendChild(button_counter_instance.$el)
},
methods: {
say: function(message) {
alert(message)
}
}
})
<script src="https://cdn.jsdelivr.net/npm/vue#2.6.10/dist/vue.js"></script>
<div id="app">
<button-counter initial_count=20 v-on:myevent="say"></button-counter>
<div ref='container'></div>
</div>

Answer 1

If I've understood what you want then you just need to listen for the event on the inner component and pass it on.
I've used arrow functions in a couple of places to avoid problems with this bindings. Otherwise I've tried to leave your code unchanged as much as possible. Changes marked with ****.
Vue.component("button-counter", {
data: function() {
return {
count: this.initial_count
}
},
props: ['initial_count'],
methods: {
add: function() {
this.count++
this.$emit('myevent', this.count)
}
},
template: '<button v-on:click="add">You clicked me {{ count }} times.</button>'
})
let app = new Vue({
el: "#app",
data() {
return {
initial_count: 10,
}
},
mounted: function() {
let initial_count = this.initial_count
let ButtonCounterComponentClass = Vue.extend({
data: function() {
return {}
},
render(h) {
return h("button-counter", {
props: {
initial_count: initial_count
},
// **** Added this ****
on: {
myevent: count => {
this.$emit('myevent', count);
}
}
// ****
})
}
})
let button_counter_instance = new ButtonCounterComponentClass()
button_counter_instance.$mount()
// **** Changed the next line ****
button_counter_instance.$on('myevent', count => {
console.log('listened!')
this.say(count)
})
this.$refs.container.appendChild(button_counter_instance.$el)
},
methods: {
say: function(message) {
alert(message)
}
}
})
<script src="https://cdn.jsdelivr.net/npm/vue#2.6.10/dist/vue.js"></script>
<div id="app">
<button-counter initial_count=20 v-on:myevent="say"></button-counter>
<div ref='container'></div>
</div>
It's important to understand that button_counter_instance is not an instance of your button-counter component. You've wrapped it in another component, albeit a component that doesn't add any extra DOM nodes. So listening on the wrapper component is not the same as listening on button-counter.
Docs for what you can pass to h: https://v2.vuejs.org/v2/guide/render-function.html#The-Data-Object-In-Depth