Reactivity

Declare state

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<h1 x-data="{ name: 'John' }" x-text="name"></h1>

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import { component$, useSignal } from "@builder.io/qwik";

export const Name = component$(() => {
  const name = useSignal("John");

  return <h1>Hello {name.value}</h1>;
});

Update state

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<h1 x-data="{ name: 'John' }" x-init="name = 'Jane'" x-text="name"></h1>

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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

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<h1
  x-data="{
  count : 10,
  get doubleCount() { return this.count * 2 }
}"
  x-text="doubleCount"
></h1>

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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

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<h1>Hello world</h1>

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export const HelloWorld = () => {
  return <div>Hello World</div>;
};

Styling

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<h1 class="title">I am red</h1>
<button style="font-size: 10rem">I am a button</button>

<style>
  .title {
    color: red;
  }
</style>

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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

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<ul x-data="{ colors: ['red', 'green', 'blue'] }">
  <template x-for="color in colors">
    <li x-text="color"></li>
  </template>
</ul>

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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

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<div x-data="{ count: 0 }">
  <p>Counter: <span x-text="count"></span></p>
  <button x-on:click="count++">+1</button>
</div>

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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

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<input x-init="$el.focus();" />

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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

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<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>

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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

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<p
  x-data="{ pageTitle: '' }"
  x-init="$nextTick(() => { pageTitle = document.title })"
>
  Page title: <span x-text="pageTitle"></span>
</p>

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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

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<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>

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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

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<!--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>

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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

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<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>

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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

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<!--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>

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import FunnyButton from "./FunnyButton";

export default function App() {
  return <FunnyButton>Click me!</FunnyButton>;
}

Slot fallback

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<!--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>

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import FunnyButton from "./FunnyButton";

export default function App() {
  return (
    <>
      <FunnyButton />
      <FunnyButton>Click me!</FunnyButton>
    </>
  );
}

Context

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Missing snippet Help us to improve Component Party logo

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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

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<div x-data="{ text: 'Hello World' }">
  <p x-text="text"></p>
  <input x-model="text" />
</div>

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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

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<div x-data="{ isAvailable: true }">
  <input id="is-available" x-model="isAvailable" type="checkbox" />
  <label for="is-available">Is available</label>
</div>

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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

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<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>

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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

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<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>

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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

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<h1>Hello world</h1>

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<!doctype html>
<html>
  <body>
    <div id="app"></div>
    <script type="module" src="./main.tsx"></script>
  </body>
</html>

Fetch data

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<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>

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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>
      )}
    />
  );
});