so#45066719

components.basic-input.js

import Ember from 'ember';

export default Ember.Component.extend({
  placeholderInternal: Ember.computed('placeholder', function() {
    // return the value passed from parent component if exists; return the default value otherwise
    return this.get('placeholder') || 'foo';
  })
});

components.super-input.js

import Ember from 'ember';

export default Ember.Component.extend({
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
{{super-input label="baz" placeholder="bar"}}
{{super-input label="baz"}}
<br>
<br>

templates.components.basic-input.hbs

{{ input placeholder=placeholderInternal }}

templates.components.super-input.hbs

<label>
  <span>{{label}}</span>
  {{ basic-input placeholder=placeholder}}
</label>

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}