Component Party 标志

Component Party 中文版

响应式

声明状态

React 标志 React

import { useState } from "react";

export default function Name() {
  const [name] = useState("张三");

  return <h1>你好 {name}</h1>;
}

Svelte 5 标志 Svelte 5

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

<h1>你好 {name}</h1>

更新状态

React 标志 React

import { useEffect, useState } from "react";

export default function Name() {
  const [name, setName] = useState("张三");

  useEffect(() => {
    setName("李四");
  }, []);

  return <h1>你好 {name}</h1>;
}

Svelte 5 标志 Svelte 5

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

<h1>你好 {name}</h1>

计算属性

React 标志 React

import { useState } from "react";

export default function DoubleCount() {
  const [count] = useState(10);
  const doubleCount = count * 2;

  return <div>{doubleCount}</div>;
}

Svelte 5 标志 Svelte 5

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

<div>{doubleCount}</div>

模板语法

最简模板

React 标志 React

export default function HelloWorld() {
  return <h1>你好，世界</h1>;
}

Svelte 5 标志 Svelte 5

<h1>你好，世界</h1>

样式

React 标志 React

import "./style.css";

export default function CssStyle() {
  return (
    <>
      <h1 className="title">我是红色的</h1>
      <button style={{ fontSize: "10rem" }}>我是一个按钮</button>
    </>
  );
}

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>

DOM循环

React 标志 React

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

Svelte 5 标志 Svelte 5

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

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

点击事件

React 标志 React

import { useState } from "react";

export default function Counter() {
  const [count, setCount] = useState(0);

  function incrementCount() {
    setCount((count) => count + 1);
  }

  return (
    <>
      <p>计数器: {count}</p>
      <button onClick={incrementCount}>+1</button>
    </>
  );
}

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>

DOM引用

React 标志 React

import { useEffect, useRef } from "react";

export default function InputFocused() {
  const inputElement = useRef(null);

  useEffect(() => inputElement.current.focus(), []);

  return <input type="text" ref={inputElement} />;
}

Svelte 5 标志 Svelte 5

<script>
  let inputElement;

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

<input bind:this={inputElement} />

条件渲染

React 标志 React

import { useState } from "react";

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

export default function TrafficLight() {
  const [lightIndex, setLightIndex] = useState(0);

  const light = TRAFFIC_LIGHTS[lightIndex];

  function nextLight() {
    setLightIndex((lightIndex + 1) % TRAFFIC_LIGHTS.length);
  }

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

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>

生命周期

组件加载时

React 标志 React

import { useState, useEffect } from "react";

export default function PageTitle() {
  const [pageTitle, setPageTitle] = useState("");

  useEffect(() => {
    setPageTitle(document.title);
  }, []);

  return <p>页面标题: {pageTitle}</p>;
}

Svelte 5 标志 Svelte 5

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

<p>页面标题: {pageTitle}</p>

组件卸载时

React 标志 React

import { useState, useEffect } from "react";

export default function Time() {
  const [time, setTime] = useState(new Date().toLocaleTimeString());

  useEffect(() => {
    const timer = setInterval(() => {
      setTime(new Date().toLocaleTimeString());
    }, 1000);

    return () => clearInterval(timer);
  }, []);

  return <p>当前时间: {time}</p>;
}

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>

组件组合

组件Props传参

React 标志 React

import UserProfile from "./UserProfile.jsx";

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

Svelte 5 标志 Svelte 5

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

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

向父组件emit事件

React 标志 React

import { useState } from "react";
import AnswerButton from "./AnswerButton.jsx";

export default function App() {
  const [isHappy, setIsHappy] = useState(true);

  function onAnswerNo() {
    setIsHappy(false);
  }

  function onAnswerYes() {
    setIsHappy(true);
  }

  return (
    <>
      <p>你快乐吗?</p>
      <AnswerButton onYes={onAnswerYes} onNo={onAnswerNo} />
      <p style={{ fontSize: 50 }}>{isHappy ? "😀" : "😥"}</p>
    </>
  );
}

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>

slot插槽

React 标志 React

import FunnyButton from "./FunnyButton.jsx";

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

Svelte 5 标志 Svelte 5

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

<FunnyButton>点我!</FunnyButton>

slot插槽内容

React 标志 React

import FunnyButton from "./FunnyButton.jsx";

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

Svelte 5 标志 Svelte 5

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

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

上下文

React 标志 React

import { useState } from "react";
import UserProfile from "./UserProfile";
import { UserContext } from "./UserContext";

export default function App() {
  const [user, setUser] = useState({
    id: 1,
    username: "abcdefg",
    email: "abcdefg@example.com",
  });

  function updateUsername(newUsername) {
    setUser((userData) => ({ ...userData, username: newUsername }));
  }

  return (
    <>
      <h1>欢迎回来, {user.username}</h1>
      <UserContext.Provider value={{ ...user, updateUsername }}>
        <UserProfile />
      </UserContext.Provider>
    </>
  );
}

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: "abcdefg@example.com",
  });

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

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

表单输入

输入框

React 标志 React

import { useState } from "react";

export default function InputHello() {
  const [text, setText] = useState("你好世界");

  function handleChange(event) {
    setText(event.target.value);
  }

  return (
    <>
      <p>{text}</p>
      <input value={text} onChange={handleChange} />
    </>
  );
}

Svelte 5 标志 Svelte 5

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

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

复选框

React 标志 React

import { useState } from "react";

export default function IsAvailable() {
  const [isAvailable, setIsAvailable] = useState(false);

  function handleChange() {
    setIsAvailable(!isAvailable);
  }

  return (
    <>
      <input
        id="is-available"
        type="checkbox"
        checked={isAvailable}
        onChange={handleChange}
      />
      <label htmlFor="is-available">这是一个checkbox</label>
    </>
  );
}

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>

单选框

React 标志 React

import { useState } from "react";

export default function PickPill() {
  const [picked, setPicked] = useState("red");

  function handleChange(event) {
    setPicked(event.target.value);
  }

  return (
    <>
      <div>你选择了: {picked}</div>

      <input
        id="blue-pill"
        checked={picked === "blue"}
        type="radio"
        value="blue"
        onChange={handleChange}
      />
      <label htmlFor="blue-pill">蓝色</label>

      <input
        id="red-pill"
        checked={picked === "red"}
        type="radio"
        value="red"
        onChange={handleChange}
      />
      <label htmlFor="red-pill">红色</label>
    </>
  );
}

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>

选择器

React 标志 React

import { useState } from "react";

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

export default function ColorSelect() {
  const [selectedColorId, setSelectedColorId] = useState(2);

  function handleChange(event) {
    setSelectedColorId(event.target.value);
  }

  return (
    <select value={selectedColorId} onChange={handleChange}>
      {colors.map((color) => (
        <option key={color.id} value={color.id} disabled={color.isDisabled}>
          {color.text}
        </option>
      ))}
    </select>
  );
}

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>

Web应用特性

渲染应用

React 标志 React

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

Svelte 5 标志 Svelte 5

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

fetch获取数据

React 标志 React

import useFetchUsers from "./useFetchUsers";

export default function App() {
  const { isLoading, error, data: users } = useFetchUsers();

  return (
    <>
      {isLoading ? (
        <p>正在获取用户信息……</p>
      ) : error ? (
        <p>获取用户信息出错</p>
      ) : (
        users && (
          <ul>
            {users.map((user) => (
              <li key={user.login.uuid}>
                <img src={user.picture.thumbnail} alt="user" />
                <p>
                  {user.name.first} {user.name.last}
                </p>
              </li>
            ))}
          </ul>
        )
      )}
    </>
  );
}

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}