Reactivity
Declare state
Update state
Qwik
import { component$, useTask$, useSignal } from "@builder.io/qwik";
export const Name = component$(() => {
const name = useSignal("John");
useTask$(() => {
name.value = "Jane";
});
return <h1>Hello {name.value}</h1>;
});
Computed state
<h1
x-data="{
count : 10,
get doubleCount() { return this.count * 2 }
}"
x-text="doubleCount"
></h1>
Qwik
import { component$, useSignal, useComputed$ } from "@builder.io/qwik";
export const DoubleCount = component$(() => {
const count = useSignal(10);
const doubleCount = useComputed$(() => count.value * 2);
return <div>{doubleCount.value}</div>;
});
Templating
Minimal template
Styling
<h1 class="title">I am red</h1>
<button style="font-size: 10rem">I am a button</button>
<style>
.title {
color: red;
}
</style>
Qwik
import { component$, useStyles$ } from "@builder.io/qwik";
export const App = component$(() => {
useStyles$(`
.title {
color: red;
}
`);
return (
<>
<h1 class="title">I am red</h1>
<button style={{ "font-size": "10rem" }}>I am a button</button>
</>
);
});
Loop
<ul x-data="{ colors: ['red', 'green', 'blue'] }">
<template x-for="color in colors">
<li x-text="color"></li>
</template>
</ul>
Qwik
import { component$ } from "@builder.io/qwik";
export const Colors = component$(() => {
const colors = ["red", "green", "blue"];
return (
<ul>
{colors.map((color) => (
<li key={color}>{color}</li>
))}
</ul>
);
});
Event click
<div x-data="{ count: 0 }">
<p>Counter: <span x-text="count"></span></p>
<button x-on:click="count++">+1</button>
</div>
Qwik
import { component$, useSignal, $ } from "@builder.io/qwik";
export const Counter = component$(() => {
const count = useSignal(0);
const incrementCount = $(() => {
count.value++;
});
return (
<>
<p>Counter: {count.value}</p>
<button onClick$={incrementCount}>Increment</button>
</>
);
});
Dom ref
Qwik
import { component$, useVisibleTask$, useSignal } from "@builder.io/qwik";
export const InputFocused = component$(() => {
const inputElement = useSignal<HTMLInputElement>();
useVisibleTask$(({ track }) => {
const el = track(inputElement);
el?.focus();
});
return <input type="text" ref={inputElement} />;
});
Conditional
<div
x-data="{
TRAFFIC_LIGHTS: ['red', 'orange', 'green'],
lightIndex: 0,
get light() { return this.TRAFFIC_LIGHTS[this.lightIndex] },
nextLight() {
this.lightIndex = (this.lightIndex + 1) % this.TRAFFIC_LIGHTS.length;
}
}"
>
<button x-on:click="nextLight">Next light</button>
<p>Light is: <span x-text="light"></span></p>
<p>
You must
<span x-show="light === 'red'">STOP</span>
<span x-show="light === 'orange'">SLOW DOWN</span>
<span x-show="light === 'green'">GO</span>
</p>
</div>
Qwik
import { $, component$, useComputed$, useSignal } from "@builder.io/qwik";
export const TRAFFIC_LIGHTS = ["red", "orange", "green"];
export const TrafficLight = component$(() => {
const lightIndex = useSignal(0);
const light = useComputed$(() => TRAFFIC_LIGHTS[lightIndex.value]);
const nextLight = $(() => {
lightIndex.value = (lightIndex.value + 1) % TRAFFIC_LIGHTS.length;
});
return (
<>
<button onClick$={nextLight}>Next light</button>
<p>Light is: {light.value}</p>
<p>
You must {light.value === "red" && <span>STOP</span>}
{light.value === "orange" && <span>SLOW DOWN</span>}
{light.value === "green" && <span>GO</span>}
</p>
</>
);
});
Lifecycle
On mount
<p
x-data="{ pageTitle: '' }"
x-init="$nextTick(() => { pageTitle = document.title })"
>
Page title: <span x-text="pageTitle"></span>
</p>
Qwik
import { component$, useVisibleTask$, useStore } from "@builder.io/qwik";
export const App = component$(() => {
const store = useStore({
pageTitle: "",
});
useVisibleTask$(() => {
store.pageTitle = document.title;
});
return <p>Page title: {store.pageTitle}</p>;
});
On unmount
<p
x-data="{
time: new Date().toLocaleTimeString(),
timer: null,
init() { this.timer = setInterval(() => (this.time = new Date().toLocaleTimeString()), 1000) },
destroy() { clearInterval(this.timer) }
}"
>
Current time: <span x-text="time"></span>
</p>
Qwik
import { component$, useVisibleTask$, useStore } from "@builder.io/qwik";
export const App = component$(() => {
const store = useStore({
time: new Date().toLocaleTimeString(),
});
useVisibleTask$(({ cleanup }) => {
const timer = setInterval(() => {
store.time = new Date().toLocaleTimeString();
}, 1000);
cleanup(() => clearInterval(timer));
});
return <p>Current time: {store.time}</p>;
});
Component composition
Props
<!--Alpine JS suggests using a server-side templating engine or another frontend framework in conjunction with Alpine to do this-->
<div
x-data="{
name: 'John',
age: 20,
favouriteColors: ['green', 'blue', 'red'],
isAvailable: true
}"
>
<p>My name is <span x-text="John"></span></p>
<p>My age is <span x-text="age"></span></p>
<p>
My favourite colors are <span x-text="favouriteColors.join(', ')"></span>
</p>
<p>I am <span x-text="isAvailable ? 'available' : 'not available'"></span></p>
</div>
Qwik
import { component$ } from "@builder.io/qwik";
import UserProfile from "./UserProfile";
const App = component$(() => {
return (
<UserProfile
name="John"
age={20}
favouriteColors={["green", "blue", "red"]}
isAvailable
/>
);
});
export default App;
Emit to parent
<div
x-data="{ isHappy: true }"
x-on:yes="isHappy = true"
x-on:no="isHappy = false"
>
<p>Are you happy?</p>
<div>
<button x-on:click="$dispatch('yes')">YES</button>
<button x-on:click="$dispatch('no')">NO</button>
</div>
<p style="font-size: 50px" x-text="isHappy ? '😀' : '😥'"></p>
</div>
Qwik
import { $, component$, useStore } from "@builder.io/qwik";
import AnswerButton from "./AnswerButton";
const App = component$(() => {
const store = useStore({
isHappy: true,
});
const onAnswerNo = $(() => {
store.isHappy = false;
});
const onAnswerYes = $(() => {
store.isHappy = true;
});
return (
<>
<p>Are you happy?</p>
<AnswerButton onYes$={onAnswerYes} onNo$={onAnswerNo} />
<p style={{ fontSize: 50 }}>{store.isHappy ? "😀" : "😥"}</p>
</>
);
});
export default App;
Slot
<!--Alpine JS suggests using a server-side templating engine or another frontend framework in conjunction with Alpine to do this-->
<button
x-data
x-text="'Click me!'"
style="
background: rgba(0, 0, 0, 0.4);
color: #fff;
padding: 10px 20px;
font-size: 30px;
border: 2px solid #fff;
margin: 8px;
transform: scale(0.9);
box-shadow: 4px 4px rgba(0, 0, 0, 0.4);
transition: transform 0.2s cubic-bezier(0.34, 1.65, 0.88, 0.925) 0s;
outline: 0;
"
>
<span>No content found</span>
</button>
Qwik
import FunnyButton from "./FunnyButton";
export default function App() {
return <FunnyButton>Click me!</FunnyButton>;
}
Slot fallback
<!--Alpine JS suggests using a server-side templating engine or another frontend framework in conjunction with Alpine to do this-->
<button
x-data
style="
background: rgba(0, 0, 0, 0.4);
color: #fff;
padding: 10px 20px;
font-size: 30px;
border: 2px solid #fff;
margin: 8px;
transform: scale(0.9);
box-shadow: 4px 4px rgba(0, 0, 0, 0.4);
transition: transform 0.2s cubic-bezier(0.34, 1.65, 0.88, 0.925) 0s;
outline: 0;
"
>
<span>No content found</span>
</button>
<button
x-data
x-text="'I got content!'"
style="
background: rgba(0, 0, 0, 0.4);
color: #fff;
padding: 10px 20px;
font-size: 30px;
border: 2px solid #fff;
margin: 8px;
transform: scale(0.9);
box-shadow: 4px 4px rgba(0, 0, 0, 0.4);
transition: transform 0.2s cubic-bezier(0.34, 1.65, 0.88, 0.925) 0s;
outline: 0;
"
>
<span>No content found</span>
</button>
Qwik
import FunnyButton from "./FunnyButton";
export default function App() {
return (
<>
<FunnyButton />
<FunnyButton>Click me!</FunnyButton>
</>
);
}
Context
Alpine
Missing snippet Help us to improve Component Party 
Qwik
import {
component$,
useStore,
useContextProvider,
createContext,
$,
} from "@builder.io/qwik";
import UserProfile from "./UserProfile";
export const UserContext = createContext("user-context");
const App = component$(() => {
const user = useStore({
id: 1,
username: "unicorn42",
email: "[email protected]",
});
const updateUsername = $((newUsername) => {
user.username = newUsername;
});
useContextProvider(UserContext, { user, updateUsername });
return (
<>
<h1>Welcome back, {user.username}</h1>
<UserProfile />
</>
);
});
export default App;
Form input
Input text
Qwik
import { component$, useSignal } from "@builder.io/qwik";
const InputHello = component$(() => {
const text = useSignal("");
return (
<>
<p>{text.value}</p>
<input bind:value={text} />
</>
);
});
export default InputHello;
Checkbox
<div x-data="{ isAvailable: true }">
<input id="is-available" x-model="isAvailable" type="checkbox" />
<label for="is-available">Is available</label>
</div>
Qwik
import { component$, useSignal } from "@builder.io/qwik";
const IsAvailable = component$(() => {
const isAvailable = useSignal(false);
return (
<>
<input id="is-available" type="checkbox" bind:checked={isAvailable} />
<label for="is-available">Is available</label>
</>
);
});
export default IsAvailable;
Radio
<div x-data="{ picked: 'red' }">
<div>Picked: <span x-text="picked"></span></div>
<input id="blue-pill" x-model="picked" type="radio" value="blue" />
<label for="blue-pill">Blue pill</label>
<input id="red-pill" x-model="picked" type="radio" value="red" />
<label for="red-pill">Red pill</label>
</div>
Qwik
import { component$, useSignal } from "@builder.io/qwik";
const PickPill = component$(() => {
const pickedColor = useSignal("red");
return (
<>
<div>Picked: {pickedColor.value}</div>
<input
id="blue-pill"
type="radio"
bind:value={pickedColor}
checked={pickedColor.value === "blue"}
value="blue"
/>
<label for="blue-pill">Blue pill</label>
<input
id="red-pill"
type="radio"
checked={pickedColor.value === "red"}
bind:value={pickedColor}
value="red"
/>
<label for="red-pill">Red pill</label>
</>
);
});
export default PickPill;
Select
<div
x-data="{
selectedColorId: 2,
colors: [
{ id: 1, text: 'red' },
{ id: 2, text: 'blue' },
{ id: 3, text: 'green' },
{ id: 4, text: 'gray', isDisabled: true }
]
}"
>
<select x-model.number="selectedColorId">
<template x-for="color in colors" x-bind:key="color.id">
<option
x-text="color.text"
x-bind:value="color.id"
x-bind:disabled="!!color.isDisabled"
x-bind:selected="color.id === selectedColorId"
></option>
</template>
</select>
</div>
Qwik
import { component$, useSignal } from "@builder.io/qwik";
export const colors = [
{ id: 1, text: "red" },
{ id: 2, text: "blue" },
{ id: 3, text: "green" },
{ id: 4, text: "gray", isDisabled: true },
];
const ColorSelect = component$(() => {
const selectedColorId = useSignal("2");
return (
<select bind:value={selectedColorId}>
{colors.map((color) => (
<option
key={color.id}
value={color.id}
disabled={color.isDisabled}
selected={`${color.id}` === selectedColorId.value}
>
{color.text}
</option>
))}
</select>
);
});
export default ColorSelect;
Webapp features
Render app
Fetch data
<div
x-data="
function fetchUsers() {
return {
users: null,
isLoading: false,
error: null,
async init() {
this.isLoading = true;
try {
this.users = (await (await fetch('https://randomuser.me/api/?results=3')).json()).results;
} catch (err) {
this.users = [];
this.error = err
}
this.isLoading = false;
},
};
}
"
>
<template x-if="isLoading">
<p>Loading...</p>
</template>
<template x-if="error">
<p>Error fetching users</p>
</template>
<template x-if="!error">
<ul>
<template x-for="user in users">
<li>
<img
:src="user.picture.thumbnail"
:alt="`picture of ${user.name.first} ${user.name.last}`"
/>
<p x-text="`${user.name.first} ${user.name.last}`"></p>
</li>
</template>
</ul>
</template>
</div>
Qwik
import { component$, useResource$, Resource } from "@builder.io/qwik";
type UsersResponse = {
results: {
picture: {
thumbnail: string;
};
name: {
first: string;
last: string;
};
}[];
};
export async function fetchUsers() {
return (await fetch("https://randomuser.me/api/?results=3")).json();
}
export const App = component$(() => {
const data = useResource$<UsersResponse>(fetchUsers);
return (
<Resource
value={data}
onPending={() => <p>Fetching users...</p>}
onRejected={() => <p>An error occurred while fetching users</p>}
onResolved={({ results: users }) => (
<ul>
{users.map((user) => (
<li>
<img src={user.picture.thumbnail} alt="user" />
<p>
{user.name.first} {user.name.last}
</p>
</li>
))}
</ul>
)}
/>
);
});