readonly and mut

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  ourValue: 1,
  actions: {
    increse: function() {
      this.set('ourValue', 1 + Math.abs(this.get('ourValue')));
    },
    onkeyup: function(e) {
      
      this.set('ourValue', e);
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
Input value: {{ourValue}}
<br><br>
Input: {{input
	value=(readonly ourValue)
  key-up='onkeyup'
  }}
<br>
<br>
<button {{action 'increse'}}>INC</button>

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"
  }
}