Composition

components.bar\.js

import Component from '@glimmer/component';

export default class extends Component {
  lastName = 'Smith'
}

components.foo\.js

import Component from '@glimmer/component';

export default class extends Component {
  firstName = 'Fred'
}

templates.application\.hbs

<p>
  We are rendering <strong>one</strong> component Foo, that component renders <strong>another</strong>: Bar. Only Foo knows about about First Name, and only Bar knows about Last Name. They can still share data between each other should they need to, by passing args down.
</p>

<Foo />

templates.components.bar\.hbs

Last name: {{this.lastName}}

templates.components.foo\.hbs

First name: {{this.firstName}}<br />
<Bar />

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}