tracked get

components.my-component\.js

import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import { action } from '@ember/object';

export default class extends Component {
  @tracked a = [1, 2, 3, 4];
	@tracked b = [2];

	get list() {
    return this.a.filter(x => !this.b.includes(x));
  }

  @action
	exclude(value) {
    this.b = [value, ...this.b];
  }
}

controllers.application\.js

import Controller from '@ember/controller';

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

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

<MyComponent />

templates.components.my-component\.hbs

{{yield}}

A: {{a}}
<br>
B: {{b}}
<br>
<br>
A - B: {{this.list}}

<br>
<br>

<button {{action "exclude" 1}}>Exclude 1</button>
<button {{action "exclude" 4}}>Exclude 4</button>

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"
  }
}