attributes

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  someAttribute: null,
  someUnsetAttribute: null,

  init() {
    this._super(...arguments);

    console.log('init', this.get('someAttribute'), this.get('someUnsetAttribute'));
    
    this.someAttribute = this.someAttribute || 'default';
    this.someUnsetAttribute = this.someUnsetAttribute || 'default';
	},
  
  didReceiveAttrs() {
    this._super(...arguments);

    console.log('didReceivedAttrs', this.get('someAttribute'), this.get('someUnsetAttribute'));
  }
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

{{my-component someAttribute="hello world"}}

templates.components.my-component.hbs

{{someAttribute}}
/
{{someUnsetAttribute}}

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"
  }
}