onpaste

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  onPaste(event) {
    event.preventDefault();
    
    event.clipboardData.items[0].getAsString(s => {
    	this.set('value', reverse(s));
    });
  }
});

function reverse(s) {
  return s.split('').reverse().join('');
}

templates.application.hbs

<input placeholder="Paste something here" value={{value}} onpaste={{action onPaste}}>

twiddle.json

{
  "version": "0.10.5",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.8.0",
    "ember-data": "2.8.0",
    "ember-template-compiler": "2.8.0",
    "ember-testing": "2.8.0"
  },
  "addons": {}
}