Call a Vue.js component method from outside the component – Dev

The best answers to the question “Call a Vue.js component method from outside the component” in the category Dev.

QUESTION:

Let’s say I have a main Vue instance that has child components. Is there a way of calling a method belonging to one of these components from outside the Vue instance entirely?

Here is an example:

var vm = new Vue({
  el: '#app',
  components: {
    'my-component': { 
      template: '#my-template',
      data: function() {
        return {
          count: 1,
        };
      },
      methods: {
        increaseCount: function() {
          this.count++;
        }
      }
    },
  }
});

$('#external-button').click(function()
{
  vm['my-component'].increaseCount(); // This doesn't work
});
<script src="http://vuejs.org/js/vue.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="app">
  
  <my-component></my-component>
  <br>
  <button id="external-button">External Button</button>
</div>
  
<template id="my-template">
  <div style="border: 1px solid; padding: 5px;">
  <p>A counter: {{ count }}</p>
  <button @click="increaseCount">Internal Button</button>
    </div>
</template>

So when I click the internal button, the increaseCount() method is bound to its click event so it gets called. There is no way to bind the event to the external button, whose click event I am listening for with jQuery, so I’ll need some other way to call increaseCount.

EDIT

It seems this works:

vm.$children[0].increaseCount();

However, this is not a good solution because I am referencing the component by its index in the children array, and with many components this is unlikely to stay constant and the code is less readable.

ANSWER:

You can set ref for child components then in parent can call via $refs:

Add ref to child component:

<my-component ref="childref"></my-component>

Add click event to parent:

<button id="external-button" @click="$refs.childref.increaseCount()">External Button</button>

var vm = new Vue({
  el: '#app',
  components: {
    'my-component': { 
      template: '#my-template',
      data: function() {
        return {
          count: 1,
        };
      },
      methods: {
        increaseCount: function() {
          this.count++;
        }
      }
    },
  }
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
  
  <my-component ref="childref"></my-component>
  <button id="external-button" @click="$refs.childref.increaseCount()">External Button</button>
</div>
  
<template id="my-template">
  <div style="border: 1px solid; padding: 2px;" ref="childref">
    <p>A counter: {{ count }}</p>
    <button @click="increaseCount">Internal Button</button>
  </div>
</template>

ANSWER:

In the end I opted for using Vue’s ref directive. This allows a component to be referenced from the parent for direct access.

E.g.

Have a compenent registered on my parent instance:

var vm = new Vue({
    el: '#app',
    components: { 'my-component': myComponent }
});

Render the component in template/html with a reference:

<my-component ref="foo"></my-component>

Now, elsewhere I can access the component externally

<script>
vm.$refs.foo.doSomething(); //assuming my component has a doSomething() method
</script>

See this fiddle for an example: https://jsfiddle.net/xmqgnbu3/1/

(old example using Vue 1: https://jsfiddle.net/6v7y6msr/)

ANSWER:

You can use Vue event system

vm.$broadcast('event-name', args)

and

 vm.$on('event-name', function())

Here is the fiddle:
http://jsfiddle.net/hfalucas/wc1gg5v4/59/

ANSWER:

For Vue2 this applies:

var bus = new Vue()

// in component A’s method

bus.$emit('id-selected', 1)

// in component B’s created hook

bus.$on('id-selected', function (id) {

  // ...
})

See here for the Vue docs.
And here is more detail on how to set up this event bus exactly.

If you’d like more info on when to use properties, events and/ or centralized state management see this article.

See below comment of Thomas regarding Vue 3.