how bubbles=false works

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  tagName: 'button',
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Event Bubbling Play Ground',
  actions: {
    handleChildClickNoop() {
      // no op
      console.log('handleChildClickNoop');
    },
    
    handleChildClickAndReturnFalse() {
      console.log('handleChildClickAndReturnFalse')
      return false;
    },
            
    handleParentClick() {
      alert('parent clicked');
    },  
  },
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

<button {{action 'handleParentClick'}}>

<button {{action 'handleChildClickNoop' bubbles=false}}>1-YES</button>
<button {{action 'handleChildClickAndReturnFalse'}}>2-NO</button>
<button {{action (action 'handleChildClickNoop') bubbles=false}}>3-YES</button>
<button {{action (action 'handleChildClickNoop' bubbles=false)}}>4-NO</button>
<button {{action (action 'handleChildClickAndReturnFalse')}}>5-NO</button>
{{#my-component  click=(action 'handleChildClickAndReturnFalse')}}
  6-YES
{{/my-component}}
{{#my-component  click=(action 'handleChildClickNoop' bubbles=false)}}
  7-NO
{{/my-component}}
</button>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}