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Component Party

Reactivity

Declare state

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<script>
export default {
  data() {
    return {
      name: "John",
    };
  },
};
</script>

<template>
  <h1>Hello {{ name }}</h1>
</template>

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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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<script>
export default {
  data() {
    return {
      name: "John",
    };
  },
  created() {
    this.name = "Jane";
  },
};
</script>

<template>
  <h1>Hello {{ name }}</h1>
</template>

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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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<script>
export default {
  data() {
    return {
      count: 10,
    };
  },
  computed: {
    doubleCount() {
      return this.count * 2;
    },
  },
};
</script>

<template>
  <div>{{ doubleCount }}</div>
</template>

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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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<template>
  <h1>Hello world</h1>
</template>

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

Styling

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

<style scoped>
.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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<script>
export default {
  data() {
    return {
      colors: ["red", "green", "blue"],
    };
  },
};
</script>

<template>
  <ul>
    <li v-for="color in colors" :key="color">
      {{ color }}
    </li>
  </ul>
</template>

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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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<script>
export default {
  data() {
    return {
      count: 0,
    };
  },
  methods: {
    incrementCount() {
      this.count++;
    },
  },
};
</script>

<template>
  <div>
    <p>Counter: {{ count }}</p>
    <button @click="incrementCount">+1</button>
  </div>
</template>

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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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<script>
export default {
  mounted() {
    this.$refs.inputElement.focus();
  },
};
</script>

<template>
  <input ref="inputElement" />
</template>

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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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<script>
export default {
  data() {
    return {
      TRAFFIC_LIGHTS: ["red", "orange", "green"],
      lightIndex: 0,
    };
  },
  computed: {
    light() {
      return this.TRAFFIC_LIGHTS[this.lightIndex];
    },
  },
  methods: {
    nextLight() {
      this.lightIndex = (this.lightIndex + 1) % this.TRAFFIC_LIGHTS.length;
    },
  },
};
</script>

<template>
  <div>
    <button @click="nextLight">Next light</button>
    <p>Light is: {{ light }}</p>
    <p>
      You must
      <span v-if="light === 'red'">STOP</span>
      <span v-else-if="light === 'orange'">SLOW DOWN</span>
      <span v-else-if="light === 'green'">GO</span>
    </p>
  </div>
</template>

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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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<script>
export default {
  data() {
    return {
      pageTitle: "",
    };
  },
  mounted() {
    this.pageTitle = document.title;
  },
};
</script>

<template>
  <p>Page title: {{ pageTitle }}</p>
</template>

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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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<script>
export default {
  data() {
    return {
      time: new Date().toLocaleTimeString(),
      timer: null,
    };
  },
  mounted() {
    this.timer = setInterval(() => {
      this.time = new Date().toLocaleTimeString();
    }, 1000);
  },
  beforeDestroy() {
    clearInterval(this.timer);
  },
};
</script>

<template>
  <p>Current time: {{ time }}</p>
</template>

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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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<script>
import UserProfile from "./UserProfile.vue";

export default {
  components: {
    UserProfile,
  },
};
</script>

<template>
  <UserProfile
    name="John"
    :age="20"
    :favorite-colors="['green', 'blue', 'red']"
    is-available
  />
</template>

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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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<script>
import AnswerButton from "./AnswerButton.vue";
export default {
  components: {
    AnswerButton,
  },
  data() {
    return {
      isHappy: true,
    };
  },
  methods: {
    onAnswerNo() {
      this.isHappy = false;
    },
    onAnswerYes() {
      this.isHappy = true;
    },
  },
};
</script>

<template>
  <div>
    <p>Are you happy?</p>
    <AnswerButton @yes="onAnswerYes" @no="onAnswerNo" />
    <p style="font-size: 50px">
      {{ isHappy ? "😀" : "😥" }}
    </p>
  </div>
</template>

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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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<script>
import FunnyButton from "./FunnyButton.vue";
export default {
  components: {
    FunnyButton,
  },
};
</script>

<template>
  <FunnyButton> Click me! </FunnyButton>
</template>

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import FunnyButton from "./FunnyButton";

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

Slot fallback

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<script>
import FunnyButton from "./FunnyButton.vue";
export default {
  components: {
    FunnyButton,
  },
};
</script>

<template>
  <div>
    <FunnyButton />
    <FunnyButton> I got content! </FunnyButton>
  </div>
</template>

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import FunnyButton from "./FunnyButton";

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

Context

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<script>
import UserProfile from "./UserProfile.vue";

export default {
  components: { UserProfile },
  provide() {
    return {
      user: Object.assign(this.user, {
        updateUsername: this.updateUsername,
      }),
    };
  },
  data() {
    return {
      user: {
        id: 1,
        username: "unicorn42",
        email: "[email protected]",
      },
    };
  },
  methods: {
    updateUsername(newUsername) {
      this.user.username = newUsername;
    },
  },
};
</script>

<template>
  <div>
    <h1>Welcome back, {{ user.username }}</h1>
    <UserProfile />
  </div>
</template>

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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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<script>
export default {
  data() {
    return {
      text: "Hello World",
    };
  },
};
</script>

<template>
  <div>
    <p>{{ text }}</p>
    <input v-model="text" />
  </div>
</template>

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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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<script>
export default {
  data() {
    return {
      isAvailable: true,
    };
  },
};
</script>

<template>
  <div>
    <input id="is-available" v-model="isAvailable" type="checkbox" />
    <label for="is-available">Is available</label>
  </div>
</template>

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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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<script>
export default {
  data() {
    return {
      picked: "red",
    };
  },
};
</script>

<template>
  <div>
    <div>Picked: {{ picked }}</div>

    <input id="blue-pill" v-model="picked" type="radio" value="blue" />
    <label for="blue-pill">Blue pill</label>

    <input id="red-pill" v-model="picked" type="radio" value="red" />
    <label for="red-pill">Red pill</label>
  </div>
</template>

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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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<script>
export default {
  data() {
    return {
      selectedColorId: 2,
      colors: [
        { id: 1, text: "red" },
        { id: 2, text: "blue" },
        { id: 3, text: "green" },
        { id: 4, text: "gray", isDisabled: true },
      ],
    };
  },
};
</script>

<template>
  <select v-model="selectedColorId">
    <option
      v-for="color in colors"
      :key="color.id"
      :value="color.id"
      :disabled="color.isDisabled"
    >
      {{ color.text }}
    </option>
  </select>
</template>

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

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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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<script>
export default {
  data() {
    return {
      isLoading: false,
      error: undefined,
      users: undefined,
    };
  },
  mounted() {
    this.fetchData();
  },
  methods: {
    async fetchData() {
      this.isLoading = true;
      try {
        const response = await fetch("https://randomuser.me/api/?results=3");
        const { results: users } = await response.json();
        this.users = users;
        this.error = undefined;
      } catch (error) {
        this.error = error;
      } finally {
        this.users = undefined;
        this.isLoading = false;
      }
    },
  },
};
</script>

<template>
  <p v-if="isLoading">Fetching users...</p>
  <p v-else-if="error">An error ocurred while fetching users</p>
  <ul v-else-if="users">
    <li v-for="user in users" :key="user.login.uuid">
      <img :src="user.picture.thumbnail" alt="user" />
      <p>
        {{ user.name.first }}
        {{ user.name.last }}
      </p>
    </li>
  </ul>
</template>

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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>
      )}
    />
  );
});