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Vue: How to bind property dynamically to a new DOM element

Say, I have a component with the following template:
<div id="root"></div>
Then somehow I call the code that appends a new element to it (using jQuery for now):
$('#root').append('<div id="a1" v-bind:styles="styles.a1"></div>')
where "styles.a1" is just an object from component's data:
data() {
return {
styles: { a1: {color: 'red'} }
};
}
I suppose the newborn element's binding will not work because Vue doesn't know anything about this new element and its binding.
But maybe there is some way to implement the desired logic?
PS I know that Vue's nature is to manipulate with data, not DOM but here is the situation I have to deal with.

If you're using Vue components you shouldn't be manipulating the DOM.
You should either use template logic for that.
<template v-if="someCondition">
<div id="a1" v-bind:styles="styles.a1"></div>
</template>
Wrap non Vue code inside it's own Vue component.
Vue.component('date-picker', {
template: '<input/>',
mounted: function() {
$(this.$el).datepicker();
},
beforeDestroy: function() {
$(this.$el).datepicker('hide').datepicker('destroy');
}
});
https://vuejsdevelopers.com/2017/05/20/vue-js-safely-jquery-plugin/
Use a custom directive.
Vue.directive('demo', {
bind: function () {
$(this.el).css({color:'#fff', backgroundColor:this.arg});
},
update: function (value) {
$(this.el).html(
'argument - ' + this.arg + '!<br>' +
'key - ' + this.key + '<br>' +
'value - ' + value);
}
});

You can bind a style without a value first,
data() {
return {
styles: { a1: '' }
};
}
then you can add data into that from an event via normal JS. (JQuery isn't even necessary here).
methods: {
quack() {
this.styles.a1 = { color: red }
}
}
Edit: I got it wrong. Seems Vue does not detect newly added elements after being mounted. So what you can do is mount the Vue instance after the appended elements are added or to re-render the whole instance with forceUpdate . (The latter will re-render the whole instance so I recommend breaking down into multiple Vue instances for the sake of performance)
ForceUpdate

Emitting events to a distant relative of a component [duplicate]

It seems that Vue.js 2.0 doesn't emit events from a grand child to his grand parent component.
Vue.component('parent', {
template: '<div>I am the parent - {{ action }} <child #eventtriggered="performAction"></child></div>',
data(){
return {
action: 'No action'
}
},
methods: {
performAction() { this.action = 'actionDone' }
}
})
Vue.component('child', {
template: '<div>I am the child <grand-child></grand-child></div>'
})
Vue.component('grand-child', {
template: '<div>I am the grand-child <button #click="doEvent">Do Event</button></div>',
methods: {
doEvent() { this.$emit('eventtriggered') }
}
})
new Vue({
el: '#app'
})
This JsFiddle solves the issue https://jsfiddle.net/y5dvkqbd/4/ , but by emtting two events:
One from grand child to middle component
Then emitting again from middle component to grand parent
Adding this middle event seems repetitive and unneccessary. Is there a way to emit directly to grand parent that I am not aware of?

Vue 2.4 introduced a way to easily pass events up the hierarchy using vm.$listeners
From https://v2.vuejs.org/v2/api/#vm-listeners :
Contains parent-scope v-on event listeners (without .native modifiers). This can be passed down to an inner component via v-on="$listeners" - useful when creating transparent wrapper components.
See the snippet below using v-on="$listeners" in the grand-child component in the child template:
Vue.component('parent', {
template:
'<div>' +
'<p>I am the parent. The value is {{displayValue}}.</p>' +
'<child #toggle-value="toggleValue"></child>' +
'</div>',
data() {
return {
value: false
}
},
methods: {
toggleValue() { this.value = !this.value }
},
computed: {
displayValue() {
return (this.value ? "ON" : "OFF")
}
}
})
Vue.component('child', {
template:
'<div class="child">' +
'<p>I am the child. I\'m just a wrapper providing some UI.</p>' +
'<grand-child v-on="$listeners"></grand-child>' +
'</div>'
})
Vue.component('grand-child', {
template:
'<div class="child">' +
'<p>I am the grand-child: ' +
'<button #click="emitToggleEvent">Toggle the value</button>' +
'</p>' +
'</div>',
methods: {
emitToggleEvent() { this.$emit('toggle-value') }
}
})
new Vue({
el: '#app'
})
.child {
padding: 10px;
border: 1px solid #ddd;
background: #f0f0f0
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<parent></parent>
</div>

NEW ANSWER (Nov-2018 update)
I discovered that we could actually do this by leveraging the $parent property in the grand child component:
this.$parent.$emit("submit", {somekey: somevalue})
Much cleaner and simpler.

The Vue community generally favors using Vuex to solve this kind of issue. Changes are made to Vuex state and the DOM representation just flows from that, eliminating the need for events in many cases.
Barring that, re-emitting would probably be the next best choice, and lastly you might choose to use an event bus as detailed in the other highly voted answer to this question.
The answer below is my original answer to this question and is not an approach I would take now, having more experience with Vue.
This is a case where I might disagree with Vue's design choice and resort to DOM.
In grand-child,
methods: {
doEvent() {
try {
this.$el.dispatchEvent(new Event("eventtriggered"));
} catch (e) {
// handle IE not supporting Event constructor
var evt = document.createEvent("Event");
evt.initEvent("eventtriggered", true, false);
this.$el.dispatchEvent(evt);
}
}
}
and in parent,
mounted(){
this.$el.addEventListener("eventtriggered", () => this.performAction())
}
Otherwise, yes, you have to re-emit, or use a bus.
Note: I added code in the doEvent method to handle IE; that code could be extracted in a reusable way.

Yes, you're correct events only go from child to parent. They don't go further, e.g. from child to grandparent.
The Vue documentation (briefly) addresses this situation in the Non Parent-Child Communication section.
The general idea is that in the grandparent component you create an empty Vue component that is passed from grandparent down to the children and grandchildren via props. The grandparent then listens for events and grandchildren emit events on that "event bus".
Some applications use a global event bus instead of a per-component event bus. Using a global event bus means you will need to have unique event names or namespacing so events don't clash between different components.
Here is an example of how to implement a simple global event bus.

If you want to be flexible and simply broadcast an event to all parents and their parents recursively up to the root, you could do something like:
let vm = this.$parent
while(vm) {
vm.$emit('submit')
vm = vm.$parent
}

Another solution will be on/emit at root node:
Uses vm.$root.$emit in grand-child, then uses vm.$root.$on at the ancestor (or anywhere you'd like).
Updated: sometimes you'd like to disable the listener at some specific situations, use vm.$off (for example: vm.$root.off('event-name') inside lifecycle hook=beforeDestroy).
Vue.component('parent', {
template: '<div><button #click="toggleEventListener()">Listener is {{eventEnable ? "On" : "Off"}}</button>I am the parent - {{ action }} <child #eventtriggered="performAction"></child></div>',
data(){
return {
action: 1,
eventEnable: false
}
},
created: function () {
this.addEventListener()
},
beforeDestroy: function () {
this.removeEventListener()
},
methods: {
performAction() { this.action += 1 },
toggleEventListener: function () {
if (this.eventEnable) {
this.removeEventListener()
} else {
this.addEventListener()
}
},
addEventListener: function () {
this.$root.$on('eventtriggered1', () => {
this.performAction()
})
this.eventEnable = true
},
removeEventListener: function () {
this.$root.$off('eventtriggered1')
this.eventEnable = false
}
}
})
Vue.component('child', {
template: '<div>I am the child <grand-child #eventtriggered="doEvent"></grand-child></div>',
methods: {
doEvent() {
//this.$emit('eventtriggered')
}
}
})
Vue.component('grand-child', {
template: '<div>I am the grand-child <button #click="doEvent">Emit Event</button></div>',
methods: {
doEvent() { this.$root.$emit('eventtriggered1') }
}
})
new Vue({
el: '#app'
})
<script src="https://unpkg.com/vue/dist/vue.js"></script>
<div id="app">
<parent></parent>
</div>

VueJS 2 components have a $parent property that contains their parent component.
That parent component also includes its own $parent property.
Then, accessing the "grandparent" component it's a matter of accessing the "parent's parent" component:
this.$parent["$parent"].$emit("myevent", { data: 123 });
Anyway, this is kinda tricky, and I recommend using a global state manager like Vuex or similar tools, as other responders have said.

I've made a short mixin based on #digout answer. You want to put it, before your Vue instance initialization (new Vue...) to use it globally in project. You can use it similarly to normal event.
Vue.mixin({
methods: {
$propagatedEmit: function (event, payload) {
let vm = this.$parent;
while (vm) {
vm.$emit(event, payload);
vm = vm.$parent;
}
}
}
})

Riffing off #kubaklam and #digout's answers, this is what I use to avoid emitting on every parent component between the grand-child and the (possibly distant) grandparent:
{
methods: {
tunnelEmit (event, ...payload) {
let vm = this
while (vm && !vm.$listeners[event]) {
vm = vm.$parent
}
if (!vm) return console.error(`no target listener for event "${event}"`)
vm.$emit(event, ...payload)
}
}
}
When building out a component with distant grand children where you don't want many/any components to be tied to the store, yet want the root component to act as a store/source of truth, this works quite well. This is similar to the data down actions up philosophy of Ember. Downside is that if you want to listen for that event on every parent in between, then this won't work. But then you can use $propogateEmit as in above answer by #kubaklam.
Edit: initial vm should be set to the component, and not the component's parent. I.e. let vm = this and not let vm = this.$parent

This is the only case when I use event bus!! For passing data from deep nested child, to not directly parent, communication.
First: Create a js file (I name it eventbus.js) with this content:
import Vue from 'vue'
Vue.prototype.$event = new Vue()
Second: In your child component emit an event:
this.$event.$emit('event_name', 'data to pass')
Third: In the parent listen to that event:
this.$event.$on('event_name', (data) => {
console.log(data)
})
Note: If you don't want that event anymore please unregister it:
this.$event.$off('event_name')
INFO: No need to read the below personal opinion
I don't like to use vuex for grand-child to grand-parent communication (Or similar communication level).
In vue.js for passing data from grand-parent to grand-child you can use provide/inject. But there is not something similar for the opposite thing. (grand-child to grand-parent) So I use event bus whenever I have to do that kind of communication.

Riffing off #digout answer. I am thinking that if the purpose is to send data to a far-ancestor then we don't need $emit at all. I did this for my edge-case and it seems to work. Yes, it could be implemented via a mixin but it doesn't have to be.
/**
* Send some content as a "message" to a named ancestor of the component calling this method.
* This is an edge-case method where you need to send a message many levels above the calling component.
* Your target component must have a receiveFromDescendant(content) method and it decides what
* to do with the content it gets.
* #param {string} name - the name of the Vue component eg name: 'myComponentName'
* #param {object} content - the message content
*/
messageNamedAncestor: function (name, content) {
let vm = this.$parent
let found = false
while (vm && !found) {
if (vm.$vnode.tag.indexOf('-' + name) > -1) {
if (vm.receiveFromDescendant) {
found = true
vm.receiveFromDescendant(content)
} else {
throw new Error(`Found the target component named ${name} but you dont have a receiveFromDescendant method there.`)
}
} else {
vm = vm.$parent
}
}
}
Given an ancestor:
export default {
name: 'myGreatAncestor',
...
methods: {
receiveFromDescendant (content) {
console.log(content)
}
}
}
A great grand-child says
// Tell the ancestor component something important
this.messageNamedAncestor('myGreatAncestor', {
importantInformation: 'Hello from your great descendant'
})

As of Vue 3, a number of fundamental changes have happened to root events:
The $on, $off and $once root methods no longer exist. There is to a certain extent something to replace this, since you can listen to root events by doing this:
createApp(App, {
// Listen for the 'expand' event
onExpand() {
console.log('expand')
}
})
Another solution are event buses, but the Vue.js documents take a dim view - they can cause maintenance headaches in the long run. You might get an ever spreading set of emits and event sinks, with no clear or central idea of how it is managed or what components could be affected elsewhere. Nonetheless, examples given by the docs of event buses are mitt and tiny-emitter.
However the docs make it clear that they recommend handling these sorts of situations in this order:
Props A convenient solution for parent / child communications.
Provide/Inject A simple way for ancestors to communicate with their descendants (although critically, not the other way around).
Vuex A way of handling global state in a clear fashion. It's important to note that this is not solely for events, or communications - Vuex was built primarily to handle state.
Essentially the choice for the OP would come down to using an event bus, or Vuex. In order to centralise the event bus, you could place it inside Vuex, if state was also needed to be globally available. Otherwise using an event bus with strict centralised controls on it's behaviour and location might help.

I really dig the way this is handled by creating a class that is bound to the window and simplifying the broadcast/listen setup to work wherever you are in the Vue app.
window.Event = new class {
constructor() {
this.vue = new Vue();
}
fire(event, data = null) {
this.vue.$emit(event, data);
}
listen() {
this.vue.$on(event, callback);
}
}
Now you can just fire / broadcast / whatever from anywhere by calling:
Event.fire('do-the-thing');
...and you can listen in a parent, grandparent, whatever you want by calling:
Event.listen('do-the-thing', () => {
alert('Doing the thing!');
});

How do I handle events between deep-tested Vue component and its furthest parent? [duplicate]

It seems that Vue.js 2.0 doesn't emit events from a grand child to his grand parent component.
Vue.component('parent', {
template: '<div>I am the parent - {{ action }} <child #eventtriggered="performAction"></child></div>',
data(){
return {
action: 'No action'
}
},
methods: {
performAction() { this.action = 'actionDone' }
}
})
Vue.component('child', {
template: '<div>I am the child <grand-child></grand-child></div>'
})
Vue.component('grand-child', {
template: '<div>I am the grand-child <button #click="doEvent">Do Event</button></div>',
methods: {
doEvent() { this.$emit('eventtriggered') }
}
})
new Vue({
el: '#app'
})
This JsFiddle solves the issue https://jsfiddle.net/y5dvkqbd/4/ , but by emtting two events:
One from grand child to middle component
Then emitting again from middle component to grand parent
Adding this middle event seems repetitive and unneccessary. Is there a way to emit directly to grand parent that I am not aware of?

Vue 2.4 introduced a way to easily pass events up the hierarchy using vm.$listeners
From https://v2.vuejs.org/v2/api/#vm-listeners :
Contains parent-scope v-on event listeners (without .native modifiers). This can be passed down to an inner component via v-on="$listeners" - useful when creating transparent wrapper components.
See the snippet below using v-on="$listeners" in the grand-child component in the child template:
Vue.component('parent', {
template:
'<div>' +
'<p>I am the parent. The value is {{displayValue}}.</p>' +
'<child #toggle-value="toggleValue"></child>' +
'</div>',
data() {
return {
value: false
}
},
methods: {
toggleValue() { this.value = !this.value }
},
computed: {
displayValue() {
return (this.value ? "ON" : "OFF")
}
}
})
Vue.component('child', {
template:
'<div class="child">' +
'<p>I am the child. I\'m just a wrapper providing some UI.</p>' +
'<grand-child v-on="$listeners"></grand-child>' +
'</div>'
})
Vue.component('grand-child', {
template:
'<div class="child">' +
'<p>I am the grand-child: ' +
'<button #click="emitToggleEvent">Toggle the value</button>' +
'</p>' +
'</div>',
methods: {
emitToggleEvent() { this.$emit('toggle-value') }
}
})
new Vue({
el: '#app'
})
.child {
padding: 10px;
border: 1px solid #ddd;
background: #f0f0f0
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<parent></parent>
</div>

NEW ANSWER (Nov-2018 update)
I discovered that we could actually do this by leveraging the $parent property in the grand child component:
this.$parent.$emit("submit", {somekey: somevalue})
Much cleaner and simpler.

The Vue community generally favors using Vuex to solve this kind of issue. Changes are made to Vuex state and the DOM representation just flows from that, eliminating the need for events in many cases.
Barring that, re-emitting would probably be the next best choice, and lastly you might choose to use an event bus as detailed in the other highly voted answer to this question.
The answer below is my original answer to this question and is not an approach I would take now, having more experience with Vue.
This is a case where I might disagree with Vue's design choice and resort to DOM.
In grand-child,
methods: {
doEvent() {
try {
this.$el.dispatchEvent(new Event("eventtriggered"));
} catch (e) {
// handle IE not supporting Event constructor
var evt = document.createEvent("Event");
evt.initEvent("eventtriggered", true, false);
this.$el.dispatchEvent(evt);
}
}
}
and in parent,
mounted(){
this.$el.addEventListener("eventtriggered", () => this.performAction())
}
Otherwise, yes, you have to re-emit, or use a bus.
Note: I added code in the doEvent method to handle IE; that code could be extracted in a reusable way.

Yes, you're correct events only go from child to parent. They don't go further, e.g. from child to grandparent.
The Vue documentation (briefly) addresses this situation in the Non Parent-Child Communication section.
The general idea is that in the grandparent component you create an empty Vue component that is passed from grandparent down to the children and grandchildren via props. The grandparent then listens for events and grandchildren emit events on that "event bus".
Some applications use a global event bus instead of a per-component event bus. Using a global event bus means you will need to have unique event names or namespacing so events don't clash between different components.
Here is an example of how to implement a simple global event bus.

If you want to be flexible and simply broadcast an event to all parents and their parents recursively up to the root, you could do something like:
let vm = this.$parent
while(vm) {
vm.$emit('submit')
vm = vm.$parent
}

Another solution will be on/emit at root node:
Uses vm.$root.$emit in grand-child, then uses vm.$root.$on at the ancestor (or anywhere you'd like).
Updated: sometimes you'd like to disable the listener at some specific situations, use vm.$off (for example: vm.$root.off('event-name') inside lifecycle hook=beforeDestroy).
Vue.component('parent', {
template: '<div><button #click="toggleEventListener()">Listener is {{eventEnable ? "On" : "Off"}}</button>I am the parent - {{ action }} <child #eventtriggered="performAction"></child></div>',
data(){
return {
action: 1,
eventEnable: false
}
},
created: function () {
this.addEventListener()
},
beforeDestroy: function () {
this.removeEventListener()
},
methods: {
performAction() { this.action += 1 },
toggleEventListener: function () {
if (this.eventEnable) {
this.removeEventListener()
} else {
this.addEventListener()
}
},
addEventListener: function () {
this.$root.$on('eventtriggered1', () => {
this.performAction()
})
this.eventEnable = true
},
removeEventListener: function () {
this.$root.$off('eventtriggered1')
this.eventEnable = false
}
}
})
Vue.component('child', {
template: '<div>I am the child <grand-child #eventtriggered="doEvent"></grand-child></div>',
methods: {
doEvent() {
//this.$emit('eventtriggered')
}
}
})
Vue.component('grand-child', {
template: '<div>I am the grand-child <button #click="doEvent">Emit Event</button></div>',
methods: {
doEvent() { this.$root.$emit('eventtriggered1') }
}
})
new Vue({
el: '#app'
})
<script src="https://unpkg.com/vue/dist/vue.js"></script>
<div id="app">
<parent></parent>
</div>

VueJS 2 components have a $parent property that contains their parent component.
That parent component also includes its own $parent property.
Then, accessing the "grandparent" component it's a matter of accessing the "parent's parent" component:
this.$parent["$parent"].$emit("myevent", { data: 123 });
Anyway, this is kinda tricky, and I recommend using a global state manager like Vuex or similar tools, as other responders have said.

I've made a short mixin based on #digout answer. You want to put it, before your Vue instance initialization (new Vue...) to use it globally in project. You can use it similarly to normal event.
Vue.mixin({
methods: {
$propagatedEmit: function (event, payload) {
let vm = this.$parent;
while (vm) {
vm.$emit(event, payload);
vm = vm.$parent;
}
}
}
})

Riffing off #kubaklam and #digout's answers, this is what I use to avoid emitting on every parent component between the grand-child and the (possibly distant) grandparent:
{
methods: {
tunnelEmit (event, ...payload) {
let vm = this
while (vm && !vm.$listeners[event]) {
vm = vm.$parent
}
if (!vm) return console.error(`no target listener for event "${event}"`)
vm.$emit(event, ...payload)
}
}
}
When building out a component with distant grand children where you don't want many/any components to be tied to the store, yet want the root component to act as a store/source of truth, this works quite well. This is similar to the data down actions up philosophy of Ember. Downside is that if you want to listen for that event on every parent in between, then this won't work. But then you can use $propogateEmit as in above answer by #kubaklam.
Edit: initial vm should be set to the component, and not the component's parent. I.e. let vm = this and not let vm = this.$parent

This is the only case when I use event bus!! For passing data from deep nested child, to not directly parent, communication.
First: Create a js file (I name it eventbus.js) with this content:
import Vue from 'vue'
Vue.prototype.$event = new Vue()
Second: In your child component emit an event:
this.$event.$emit('event_name', 'data to pass')
Third: In the parent listen to that event:
this.$event.$on('event_name', (data) => {
console.log(data)
})
Note: If you don't want that event anymore please unregister it:
this.$event.$off('event_name')
INFO: No need to read the below personal opinion
I don't like to use vuex for grand-child to grand-parent communication (Or similar communication level).
In vue.js for passing data from grand-parent to grand-child you can use provide/inject. But there is not something similar for the opposite thing. (grand-child to grand-parent) So I use event bus whenever I have to do that kind of communication.

Riffing off #digout answer. I am thinking that if the purpose is to send data to a far-ancestor then we don't need $emit at all. I did this for my edge-case and it seems to work. Yes, it could be implemented via a mixin but it doesn't have to be.
/**
* Send some content as a "message" to a named ancestor of the component calling this method.
* This is an edge-case method where you need to send a message many levels above the calling component.
* Your target component must have a receiveFromDescendant(content) method and it decides what
* to do with the content it gets.
* #param {string} name - the name of the Vue component eg name: 'myComponentName'
* #param {object} content - the message content
*/
messageNamedAncestor: function (name, content) {
let vm = this.$parent
let found = false
while (vm && !found) {
if (vm.$vnode.tag.indexOf('-' + name) > -1) {
if (vm.receiveFromDescendant) {
found = true
vm.receiveFromDescendant(content)
} else {
throw new Error(`Found the target component named ${name} but you dont have a receiveFromDescendant method there.`)
}
} else {
vm = vm.$parent
}
}
}
Given an ancestor:
export default {
name: 'myGreatAncestor',
...
methods: {
receiveFromDescendant (content) {
console.log(content)
}
}
}
A great grand-child says
// Tell the ancestor component something important
this.messageNamedAncestor('myGreatAncestor', {
importantInformation: 'Hello from your great descendant'
})

As of Vue 3, a number of fundamental changes have happened to root events:
The $on, $off and $once root methods no longer exist. There is to a certain extent something to replace this, since you can listen to root events by doing this:
createApp(App, {
// Listen for the 'expand' event
onExpand() {
console.log('expand')
}
})
Another solution are event buses, but the Vue.js documents take a dim view - they can cause maintenance headaches in the long run. You might get an ever spreading set of emits and event sinks, with no clear or central idea of how it is managed or what components could be affected elsewhere. Nonetheless, examples given by the docs of event buses are mitt and tiny-emitter.
However the docs make it clear that they recommend handling these sorts of situations in this order:
Props A convenient solution for parent / child communications.
Provide/Inject A simple way for ancestors to communicate with their descendants (although critically, not the other way around).
Vuex A way of handling global state in a clear fashion. It's important to note that this is not solely for events, or communications - Vuex was built primarily to handle state.
Essentially the choice for the OP would come down to using an event bus, or Vuex. In order to centralise the event bus, you could place it inside Vuex, if state was also needed to be globally available. Otherwise using an event bus with strict centralised controls on it's behaviour and location might help.

I really dig the way this is handled by creating a class that is bound to the window and simplifying the broadcast/listen setup to work wherever you are in the Vue app.
window.Event = new class {
constructor() {
this.vue = new Vue();
}
fire(event, data = null) {
this.vue.$emit(event, data);
}
listen() {
this.vue.$on(event, callback);
}
}
Now you can just fire / broadcast / whatever from anywhere by calling:
Event.fire('do-the-thing');
...and you can listen in a parent, grandparent, whatever you want by calling:
Event.listen('do-the-thing', () => {
alert('Doing the thing!');
});

Vue.js - How to call method from another component

I am using Vue.Js v2. I want to call component1->c1method in component2->c2method for reload data after submitting.
Vue.component('component1', {
methods: {
c1method: function(){
alert('this is c1method')
},
}
})
Vue.component('component2', {
methods: {
c2method: function(){
component('component1').c1method()//like this
},
}
})

For non-parent-child relation, then this is the same as this one. Call one method, apparently any method of a component from any other component. Just add a $on function to the $root instance and call form any other component accessing the $root and calling $emit function.
On First component
....
mounted() {
this.$root.$on('component1', () => {
// your code goes here
this.c1method()
}
}
and in the second component call the $emit function in $root
...
c2method: function(){
this.$root.$emit('component1') //like this
},
It acts more like a socket. Reference here
https://stackoverflow.com/a/50343039/6090215

// Component A
Vue.component('A', {
created() {
this.$root.$refs.A = this;
},
methods: {
foo: function() {
alert('this is A.foo');
}
}
});
// Component B
Vue.component('B', {
methods: {
bar: function() {
this.$root.$refs.A.foo();
}
}
});

No need for hacky solutions.
In vuejs we can create events that can be listened globally.
With this feature, whenever we want to call our beloved function, we just emit this event.
Now, we just listen to this event all the time from the component. whenever this global event happens we can execute our method we want to call.
It's pretty simple:
you go to main.js, before creating the vue instance, write this:
export const eventBus = new Vue(); // added line
new Vue({
...
...
...
render: h => h(App)
}).$mount('#app');
Anywhere we want to fire the target function, we dont fire it, we just emit this event:
eventBus.$emit('fireMethod');
Now in our component that has the target function, we always listen to this event:
created() {
eventBus.$on('fireMethod', () => {
this.myBelovedMethod();
})
}
Dont forget to import eventBus in top.
import {eventBus} from "path/to/main.js";
thats it, few lines of code, no hacky, all vuejs power.

The docs address this situation
https://v2.vuejs.org/v2/guide/components.html#Non-Parent-Child-Communication
If your components have the same parent, you can emit an event that the parent listens to. Then with the ref property set, you can call the c1method from the parent.
https://v2.vuejs.org/v2/guide/components.html#Child-Component-Refs

Try this out.
<template>
...
<component1 ref='componentOne'>
...
</template>
<script>
Vue.component('component2', {
methods: {
c2method: function(){
this.$refs.componentOne.c1method();
}
}
});
</script>

If anyone is looking for a solution in Vue.js v3:
https://v3-migration.vuejs.org/breaking-changes/events-api.html#event-bus
https://github.com/developit/mitt#install
import mitt from 'mitt'
const emitter = mitt()
// listen to an event
emitter.on('foo', e => console.log('foo', e) )
// listen to all events
emitter.on('*', (type, e) => console.log(type, e) )
// fire an event
emitter.emit('foo', { a: 'b' })
// clearing all events
emitter.all.clear()

how communicate two separate .vue files?

In a project with vue.js 2:
I've a component living in a .vue file that represents a list of elements. Also, I've a sidebar that is the summary of this list. This sidebar is another component in a .vue file.
So, how I can keep communication between each them, for example, if I removed a element from a list, reflect the change in a var declared in sidebar that is the total number of elements?To ilustrate:
SideBar.vue
<template>
...
<span></span> ===> here I need total of elements listed in ListElements.vue
...
<template>
ListElements.vue
<template>
...
#click="deleteEntry"
...
<template>
<script>
methods: {
deleteEntry(entry) {
//here I need to notify to SideBar.vue in order to update the total of elements in the this.entries list.
let index = this.entries.indexOf(entry);
if (window.confirm('Are you sure you want to delete this time entry?')) {
this.entries.splice(index, 1);
}
}
</script>

OK, I've created a simplified example of how this works. Your bus needs to be global so it is accessible by all Vue components, this simply means placing it outside of all other components and view models:
var bus = new Vue({});
var vm = new Vue({
// Main view model has access to bus
el: '#app'
});
Then you just need to emit the event on the bus on some event and catch that in the other component:
Component one emits a message to the bus on keyup:
Vue.component('component-one', {
template: '<div>Enter a message: <input v-model="msg" v-on:keyup="updateMessage"> </div>',
methods: {
updateMessage() {
bus.$emit('msg', this.msg);
}
},
data() {
return {
msg: ""
}
}
});
Component-two listens for the message:
Vue.component('component-two', {
template: "<div><b>Component one says: {{ msg }}</b></div>",
created() {
bus.$on('msg', (msg) => {
this.msg = msg;
});
},
data() {
return {
msg: ""
}
}
});
Here's the fiddle: https://jsfiddle.net/v7o6d2vL/
For your single page components to get access the the bus you just need to make sure your bus is in the global scope, which you can do by using window:
window.bus = new Vue({});
you can then use bus.$emit() and bus.$on() inside your components as normal