Reactivity
Declare state
Ember Polaris
import Component from "@glimmer/component";
export default class NameComponent extends Component {
name = "John";
<template>
<h1>Hello {{this.name}}</h1>
</template>
}
Aurelia 1
<template>
<h1>Hello ${name}</h1>
</template>
Update state
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
export default class CounterComponent extends Component {
@tracked name = "John";
constructor(owner, args) {
super(owner, args);
this.name = "Jane";
}
<template>
<h1>Hello {{this.name}}</h1>
</template>
}
Aurelia 1
<template>
<h1>Hello ${name}</h1>
</template>
Computed state
Ember Polaris
import Component, { tracked } from "@glimmer/component";
export default class DoubleCount extends Component {
@tracked count = 10;
get doubleCount() {
return this.count * 2;
}
<template>
<div>{{this.doubleCount}}</div>
</template>
}
Aurelia 1
<template>
<div>${doubleCount}</div>
</template>
Templating
Minimal template
Ember Polaris
<template>
<h1>Hello world</h1>
</template>
Aurelia 1
<template>
<h1>Hello world</h1>
</template>
Styling
Ember Polaris
<template>
<h1 class="title">I am red</h1>
<button style="font-size: 10rem;">I am a button</button>
<style>
.title {
color: red;
}
</style>
</template>
Aurelia 1
.title {
color: red;
}
Loop
Ember Polaris
const colors = ["red", "green", "blue"];
<template>
<ul>
{{#each colors as |color|}}
<li>{{color}}</li>
{{/each}}
</ul>
</template>
Aurelia 1
<template>
<ul>
<li repeat.for="color of colors">${color}</li>
</ul>
</template>
Event click
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
export default class Counter extends Component {
@tracked count = 0;
incrementCount = () => this.count++;
<template>
<p>Counter: {{this.count}}</p>
<button {{on "click" this.incrementCount}}>+1</button>
</template>
}
Aurelia 1
<template>
<p>Counter: ${count}</p>
<button click.trigger="incrementCount()">+1</button>
</template>
Dom ref
Ember Polaris
import { modifier } from "ember-modifier";
const autofocus = modifier((element) => element.focus());
<template>
<input {{autofocus}} />
</template>
Aurelia 1
<template>
<input ref="inputElement" />
</template>
Conditional
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
const TRAFFIC_LIGHTS = ["red", "orange", "green"];
export default class TrafficLight extends Component {
@tracked lightIndex = 0;
get light() {
return TRAFFIC_LIGHTS[this.lightIndex];
}
nextLight = () => {
this.lightIndex = (this.lightIndex + 1) % TRAFFIC_LIGHTS.length;
};
<template>
<button {{on "click" this.nextLight}}>Next light</button>
<p>Light is: {{this.light}}</p>
<p>
You must
{{#if (eq this.light "red")}}
STOP
{{else if (eq this.light "orange")}}
SLOW DOWN
{{else if (eq this.light "green")}}
GO
{{/if}}
</p>
</template>
}
Aurelia 1
<template>
<button click.trigger="nextLight()">Next light</button>
<p>Light is: ${light}</p>
<p>
You must
<span if.bind="light === 'red'">STOP</span>
<span if.bind="light === 'orange'">SLOW DOWN</span>
<span if.bind="light === 'green'">GO</span>
</p>
</template>
Lifecycle
On mount
Ember Polaris
const pageTitle = () => document.title;
<template>
<p>Page title is: {{(pageTitle)}}</p>
</template>
Aurelia 1
<template>
<p>Page title is: ${pageTitle}</p>
</template>
On unmount
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
import { registerDestructor } from "@ember/destroyable";
export default class Time extends Component {
@tracked time = new Date().toLocaleTimeString();
constructor(owner, args) {
super(owner, args);
let timer = setInterval(() => {
this.time = new Date().toLocaleTimeString();
}, 1000);
registerDestructor(this, () => clearInterval(timer));
}
<template>
<p>Current time: {{this.time}}</p>
</template>
}
Aurelia 1
<template>
<p>Current time: ${time}</p>
</template>
Component composition
Props
Ember Polaris
import UserProfile from "./user-profile.gjs";
const favoriteColors = ["green", "blue", "red"];
<template>
<UserProfile
@name="John"
@age={{20}}
@favouriteColors={{favoriteColors}}
@isAvailable={{true}}
/>
</template>
Aurelia 1
<template>
<require from="./user-profile"></require>
<user-profile
name.bind="name"
age.bind="age"
favourite-colors.bind="colors"
is-available.bind="available"
></user-profile>
</template>
Emit to parent
Ember Polaris
<template>
<button {{on "click" @onYes}}> YES </button>
<button {{on "click" @onNo}}> NO </button>
</template>
Aurelia 1
<template>
<require from="./answer-button"></require>
<p>Can I come ?</p>
<answer-button action-handler.call="handleAnswer(reply)"></answer-button>
<p style="font-size: 50px">${isHappy ? "😀" : "😥"}</p>
</template>
Slot
Ember Polaris
import FunnyButton from "./funny-button";
<template>
<FunnyButton>Click me!</FunnyButton>
</template>
Aurelia 1
<template>
<require from="./funny-button"></require>
<funny-button>Click me !</funny-button>
</template>
Slot fallback
Ember Polaris
import FunnyButton from "./funny-button";
<template>
<FunnyButton />
<FunnyButton>I got content!</FunnyButton>
</template>
Aurelia 1
<template>
<require from="./funny-button"></require>
<funny-button></funny-button>
<funny-button>Click me !</funny-button>
</template>
Context
Ember Polaris
import UserProfile from "./user-profile";
<template>
<UserProfile />
</template>
Aurelia 1
Missing snippet Help us to improve Component Party 
Form input
Input text
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
export default class InputHello extends Component {
@tracked text = "Hello World";
handleInput = (event) => (this.text = event.target.value);
<template>
<p>{{this.text}}</p>
<input value={{this.text}} {{on "input" this.handleInput}} />
</template>
}
Aurelia 1
<template>
<p>${text}</p>
<input value.bind="text" />
</template>
Checkbox
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
export default class InputHello extends Component {
@tracked isAvailable = false;
handleChange = (event) => (this.isAvailable = event.target.checked);
<template>
<input
id="is-available"
type="checkbox"
checked={{this.isAvailable}}
{{on "change" this.handleChange}}
/>
<label for="is-available">Is available</label>
</template>
}
Aurelia 1
<template>
<input id="is-available" type="checkbox" checked.bind="isAvailable" />
<label for="is-available">Is available</label>: ${isAvailable}
</template>
Radio
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
export default class PickPill extends Component {
@tracked picked = "red";
handleChange = (event) => (this.picked = event.target.value);
<template>
<div>Picked: {{this.picked}}</div>
<input
id="blue-pill"
type="radio"
value="blue"
checked={{eq this.picked "blue"}}
{{on "change" this.handleChange}}
/>
<label htmlFor="blue-pill">Blue pill</label>
<input
id="red-pill"
type="radio"
value="red"
checked={{eq this.picked "red"}}
{{on "change" this.handleChange}}
/>
<label htmlFor="red-pill">Red pill</label>
</template>
}
Aurelia 1
<template>
<div>Picked: ${picked}</div>
<input id="blue-pill" checked.bind="picked" type="radio" value="blue" />
<label for="blue-pill">Blue pill</label>
<input id="red-pill" checked.bind="picked" type="radio" value="red" />
<label for="red-pill">Red pill</label>
</template>
Select
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
export default class ColorSelect extends Component {
@tracked selectedColorId = 2;
select = (event) => (this.selectedColorId = event.target.value);
isSelected = (colorId) => this.selectedColorId === colorId;
colors = [
{ id: 1, text: "red" },
{ id: 2, text: "blue" },
{ id: 3, text: "green" },
{ id: 4, text: "gray", isDisabled: true },
];
<template>
<select {{on "change" this.select}}>
{{#each this.colors as |color|}}
<option
value={{color.id}}
disabled={{color.isDisabled}}
selected={{this.isSelected color.id}}
>
{{color.text}}
</option>
{{/each}}
</select>
</template>
}
Aurelia 1
<template>
<select value.bind="selectedColorId">
<option value="">Select A Color</option>
<option
repeat.for="color of colors"
value.bind="color.id"
disabled.bind="color.isDisabled"
>
${color.text}
</option>
</select>
</template>
Webapp features
Render app
Ember Polaris
<!doctype html>
<html>
<body>
<script type="module" src="./index.js"></script>
</body>
</html>
Aurelia 1
Missing snippet Help us to improve Component Party 
Fetch data
Ember Polaris
import Component from "@glimmer/component";
import { tracked } from "@glimmer/tracking";
class State {
@tracked isLoading = false;
@tracked error = null;
@tracked data = null;
}
function fetchUsers() {
let state = new State();
async function fetchData() {
try {
let response = await fetch("https://randomuser.me/api/?results=3");
let { results: users } = await response.json();
state.data = users;
state.error = null;
} catch (err) {
state.data = null;
state.error = err;
}
state.isLoading = false;
}
fetchData();
return state;
}
export default class App extends Component {
<template>
{{#let (this.fetchUsers) as |request|}}
{{#if request.isLoading}}
<p>Fetching users...</p>
{{else if request.error}}
<p>An error occurred while fetching users</p>
{{else}}
<ul>
{{#each request.data as |user|}}
<li>
<img src={{user.picture.thumbnail}} alt="user" />
<p>{{user.name.first}} {{user.name.last}}</p>
</li>
{{/each}}
</ul>
{{/if}}
{{/let}}
</template>
}
Aurelia 1
<template>
<p if.bind="isLoading">Fetching users...</p>
<p if.bind="error">An error ocurred while fetching users</p>
<ul if.bind="users">
<li repeat.for="user of users">
<img src.bind="user.picture.thumbnail" alt="user" />
<p>${ user.name.first } ${ user.name.last }</p>
</li>
</ul>
</template>