SO 53344020

components.child-component.js

import Ember from 'ember';


export default Ember.Component.extend({
  line1: "Say Hi!",
  line2: "Say Yeah!",
  
  changeAction(newAction) {
    switch (newAction) {
      case "1":
        this.onActionChange(this.action1);
        break;
        
      case "2":
        this.onActionChange(this.action2);
        break;
        
      default:
        this.onActionChange(undefined);
        break;
    }
  },
  
  action1: Ember.computed(function(){
    const that = this;
    return function() {
      alert(that.line1);
    }
  }),
  
  action2: Ember.computed(function(){
    const that = this;
    return function() {
      alert(that.line2);
    }
  })
});

components.parent-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  childishAction() {
    if (typeof this.childAction === 'function') {
      this.childAction();
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

<h1>Welcome to 53344020-1</h1>
<br>
<br>
{{parent-component}}
<br>
<br>

templates.components.child-component.hbs

<select  onchange={{action changeAction value="target.value"}}>
		<option>Choose something</option>
		<option value="1">Action 1</option>
    <option value="2">Action 2</option>
</select>

templates.components.parent-component.hbs

{{child-component onActionChange=(action (mut childAction))}}
<div><button disabled={{unless childAction true false}} onclick={{action childishAction}}>Let's do it!</button></div>

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"
  }
}