I have a ponent which is sometimes being used as a child of a parent and sometimes it does not have any parent.

This ponent emits a particular event which either being caught by the parent ( if subscribed) or I would like to handle it by this ponent itself.

So at run time, How do I programmatically check

if (someone is listening to the event){
    let them catch and handle it
}else {
    let's handle it by our own
}

I have a ponent which is sometimes being used as a child of a parent and sometimes it does not have any parent.

This ponent emits a particular event which either being caught by the parent ( if subscribed) or I would like to handle it by this ponent itself.

So at run time, How do I programmatically check

if (someone is listening to the event){
    let them catch and handle it
}else {
    let's handle it by our own
}

• javascript
• vue.js
• vuejs2
• vue-ponent

2 Answers 2

This allows you to check listeners passed to a ponent:

this.$listeners;

It returns the parent scope event listeners. See the doc here.

In particular for your use-case:

// To check whether the "myEvent" event is listened to
if (this.$listeners.myEvent){
  // let them catch and handle it
} else {
  // let's handle it by our own
}

You can pass a boolean prop from your parent.

In Parent Component :

<Child :isParent='true'></Child>

In Child Component :

props : {
  isParent : Boolean
},

methods : {
  actionEvent : function(){
    if(this.isParent){
      // Emit event
    }
    else{
      // Take care over here.
    }
  }
}