响应式

声明状态

Svelte 5 标志 Svelte 5

<script>
  let name = $state("张三");
</script>

<h1>你好 {name}</h1>

Qwik 标志 Qwik

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

export const Name = component$(() => {
  const name = useSignal("张三");

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

更新状态

Svelte 5 标志 Svelte 5

<script>
  let name = $state("张三");
  name = "李四";
</script>

<h1>你好 {name}</h1>

Qwik 标志 Qwik

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

export const Name = component$(() => {
  const name = useSignal("张三");

  useTask$(() => {
    name.value = "李四";
  });

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

计算属性

Svelte 5 标志 Svelte 5

<script>
  let count = $state(10);
  const doubleCount = $derived(count * 2);
</script>

<div>{doubleCount}</div>

Qwik 标志 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>;
});

模板语法

最简模板

Svelte 5 标志 Svelte 5

<h1>你好,世界</h1>

Qwik 标志 Qwik

export const HelloWorld = () => {
  return <div>你好,世界</div>;
};

样式

Svelte 5 标志 Svelte 5

<h1 class="title">我是红色的</h1>
<button style="font-size: 10rem;">我是一个按钮</button>

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

Qwik 标志 Qwik

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

export const App = component$(() => {
  useStyles$(`
    .title {
      color: red;
    }
    `);

  return (
    <>
      <h1 class="title">我是红色的</h1>
      <button style={{ "font-size": "10rem" }}>我是一个按钮</button>
    </>
  );
});

DOM循环

Svelte 5 标志 Svelte 5

<script>
  const colors = ["红", "绿", "蓝"];
</script>

<ul>
  {#each colors as color (color)}
    <li>{color}</li>
  {/each}
</ul>

Qwik 标志 Qwik

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

export const Colors = component$(() => {
  const colors = ["红", "绿", "蓝"];
  return (
    <ul>
      {colors.map((color) => (
        <li key={color}>{color}</li>
      ))}
    </ul>
  );
});

点击事件

Svelte 5 标志 Svelte 5

<script>
  let count = $state(0);

  function incrementCount() {
    count++;
  }
</script>

<p>计数器: {count}</p>
<button onclick={incrementCount}>+1</button>

Qwik 标志 Qwik

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

export const Counter = component$(() => {
  const count = useSignal(0);

  const incrementCount = $(() => {
    count.value++;
  });

  return (
    <>
      <p>计数器: {count.value}</p>
      <button onClick$={incrementCount}>Increment</button>
    </>
  );
});

DOM引用

Svelte 5 标志 Svelte 5

<script>
  let inputElement;

  $effect(() => {
    inputElement.focus();
  });
</script>

<input bind:this={inputElement} />

Qwik 标志 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} />;
});

条件渲染

Svelte 5 标志 Svelte 5

<script>
  const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];
  let lightIndex = $state(0);

  const light = $derived(TRAFFIC_LIGHTS[lightIndex]);

  function nextLight() {
    lightIndex = (lightIndex + 1) % TRAFFIC_LIGHTS.length;
  }
</script>

<button onclick={nextLight}>下一个灯</button>
<p>现在亮着的是: {light}</p>
<p>
  你应该
  {#if light === "红灯"}
    <span>停下</span>
  {:else if light === "黄灯"}
    <span>慢行</span>
  {:else if light === "绿灯"}
    <span>赶紧走</span>
  {/if}
</p>

Qwik 标志 Qwik

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

export const TRAFFIC_LIGHTS = ["红灯", "黄灯", "绿灯"];

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}>下一个灯</button>
      <p>现在亮着的是: {light.value}</p>
      <p>
        你应该 {light.value === "红灯" && <span>停下</span>}
        {light.value === "黄灯" && <span>慢行</span>}
        {light.value === "绿灯" && <span>赶紧走</span>}
      </p>
    </>
  );
});

生命周期

组件加载时

Svelte 5 标志 Svelte 5

<script>
  let pageTitle = $state("");
  $effect(() => {
    pageTitle = document.title;
  });
</script>

<p>页面标题: {pageTitle}</p>

Qwik 标志 Qwik

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

export const App = component$(() => {
  const store = useStore({
    pageTitle: "",
  });

  useVisibleTask$(() => {
    store.pageTitle = document.title;
  });

  return <p>页面标题: {store.pageTitle}</p>;
});

组件卸载时

Svelte 5 标志 Svelte 5

<script>
  let time = $state(new Date().toLocaleTimeString());

  $effect(() => {
    const timer = setInterval(() => {
      time = new Date().toLocaleTimeString();
    }, 1000);

    return () => clearInterval(timer);
  });
</script>

<p>当前时间: {time}</p>

Qwik 标志 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>当前时间: {store.time}</p>;
});

组件组合

组件Props传参

Svelte 5 标志 Svelte 5

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

<UserProfile
  name="张三"
  age={20}
  favouriteColors={["green", "blue", "red"]}
  isAvailable
/>

Qwik 标志 Qwik

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

const App = component$(() => {
  return (
    <UserProfile
      name="张三"
      age={20}
      favouriteColors={["green", "blue", "red"]}
      isAvailable
    />
  );
});

export default App;

向父组件emit事件

Svelte 5 标志 Svelte 5

<script>
  import AnswerButton from "./AnswerButton.svelte";

  let isHappy = $state(true);

  function onAnswerNo() {
    isHappy = false;
  }

  function onAnswerYes() {
    isHappy = true;
  }
</script>

<p>你快乐吗?</p>
<AnswerButton onYes={onAnswerYes} onNo={onAnswerNo} />
<p style="font-size: 50px;">{isHappy ? "😀" : "😥"}</p>

Qwik 标志 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>你快乐吗?</p>
      <AnswerButton onYes$={onAnswerYes} onNo$={onAnswerNo} />
      <p style={{ fontSize: 50 }}>{store.isHappy ? "😀" : "😥"}</p>
    </>
  );
});

export default App;

slot插槽

Svelte 5 标志 Svelte 5

<script>
  import FunnyButton from "./FunnyButton.svelte";
</script>

<FunnyButton>点我!</FunnyButton>

Qwik 标志 Qwik

import FunnyButton from "./FunnyButton";

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

slot插槽内容

Svelte 5 标志 Svelte 5

<script>
  import FunnyButton from "./FunnyButton.svelte";
</script>

<FunnyButton />
<FunnyButton>这是传到slot的内容!</FunnyButton>

Qwik 标志 Qwik

import FunnyButton from "./FunnyButton";

export default function App() {
  return (
    <>
      <FunnyButton />
      <FunnyButton>这是传到slot的内容!</FunnyButton>
    </>
  );
}

上下文

Svelte 5 标志 Svelte 5

<script>
  import { setContext } from "svelte";
  import UserProfile from "./UserProfile.svelte";
  import createUserState from "./createUserState.svelte.js";

  const user = createUserState({
    id: 1,
    username: "abcdefg",
    email: "[email protected]",
  });

  setContext("user", user);
</script>

<h1>欢迎回来, {user.username}</h1>
<UserProfile />

Qwik 标志 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: "abcdefg",
    email: "[email protected]",
  });

  const updateUsername = $((newUsername) => {
    user.username = newUsername;
  });

  useContextProvider(UserContext, { user, updateUsername });

  return (
    <>
      <h1>欢迎回来, {user.username}</h1>
      <UserProfile />
    </>
  );
});

export default App;

表单输入

输入框

Svelte 5 标志 Svelte 5

<script>
  let text = $state("你好世界");
</script>

<p>{text}</p>
<input bind:value={text} />

Qwik 标志 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;

复选框

Svelte 5 标志 Svelte 5

<script>
  let isAvailable = $state(false);
</script>

<input id="is-available" type="checkbox" bind:checked={isAvailable} />
<label for="is-available">这是一个checkbox</label>

Qwik 标志 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">这是一个checkbox</label>
    </>
  );
});

export default IsAvailable;

单选框

Svelte 5 标志 Svelte 5

<script>
  let picked = $state("red");
</script>

<div>你选择了: {picked}</div>

<input id="blue-pill" bind:group={picked} type="radio" value="blue" />
<label for="blue-pill">蓝色</label>

<input id="red-pill" bind:group={picked} type="radio" value="red" />
<label for="red-pill">红色</label>

Qwik 标志 Qwik

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

const PickPill = component$(() => {
  const pickedColor = useSignal("red");

  return (
    <>
      <div>你选择了: {pickedColor.value}</div>
      <input
        id="blue-pill"
        type="radio"
        bind:value={pickedColor}
        checked={pickedColor.value === "blue"}
        value="blue"
      />
      <label for="blue-pill">蓝色</label>

      <input
        id="red-pill"
        type="radio"
        checked={pickedColor.value === "red"}
        bind:value={pickedColor}
        value="red"
      />
      <label for="red-pill">红色</label>
    </>
  );
});

export default PickPill;

选择器

Svelte 5 标志 Svelte 5

<script>
  let selectedColorId = $state(2);

  const colors = [
    { id: 1, text: "红" },
    { id: 2, text: "蓝" },
    { id: 3, text: "绿" },
    { id: 4, text: "灰", isDisabled: true },
  ];
</script>

<select bind:value={selectedColorId}>
  {#each colors as color}
    <option value={color.id} disabled={color.isDisabled}>
      {color.text}
    </option>
  {/each}
</select>

Qwik 标志 Qwik

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

export const colors = [
  { id: 1, text: "红" },
  { id: 2, text: "蓝" },
  { id: 3, text: "绿" },
  { id: 4, text: "灰", 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;

Web应用特性

渲染应用

Svelte 5 标志 Svelte 5

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

Qwik 标志 Qwik

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

fetch获取数据

Svelte 5 标志 Svelte 5

<script>
  import useFetchUsers from "./useFetchUsers.svelte.js";

  const response = useFetchUsers();
</script>

{#if response.isLoading}
  <p>正在获取用户信息……</p>
{:else if response.error}
  <p>获取用户信息出错</p>
{:else if response.users}
  <ul>
    {#each response.users as user}
      <li>
        <img src={user.picture.thumbnail} alt="user" />
        <p>
          {user.name.first}
          {user.name.last}
        </p>
      </li>
    {/each}
  </ul>
{/if}

Qwik 标志 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>正在获取用户信息……</p>}
      onRejected={() => <p>获取用户信息出错</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>
      )}
    />
  );
});