Two Way Bound Textarea

components.test-textarea.js

import Ember from 'ember';

export default Ember.Component.extend({
  value: '',
  actions: {
  	input: function(e) {
      let value = e.target.value,
          filteredValue = value.toUpperCase().replace(/[\r\n\v]/g, '');
      
      console.log('before', value, 'after', filteredValue, 'end');
    	this.set('value', filteredValue);
      
      // Uncomment this to make it work
      //e.target.value = this.get('value');
    }
  },
});

controllers.application.js

import Ember from 'ember';

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

templates.application.hbs

{{test-textarea}}

templates.components.test-textarea.hbs

<textarea oninput={{action 'input'}} value={{value}}></textarea>

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"
  }
}