guid-for helper

controllers.application\.js

import Controller from '@ember/controller';

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
}

helpers.unique-id\.js

import { helper } from '@ember/component/helper';
import { guidFor } from '@ember/object/internals';

export default helper(() => guidFor({}));

templates.application\.hbs

{{#let (unique-id) as |id|}}
  <fieldset>
	  <legend>A label, input, and alert tied to together with {{id}}</legend>
	  
    <label for="{{id}}-input">Email</label>
		
    <input
      type="email"
      id="{{id}}-input"
      aria-describedby="{{id}}-alert"
    >
    
    <span id="{{id}}-alert" role="alert">
      Please enter a valid email address.
    </span>
  </fieldset>
{{/let}}

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"
  }
}