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>;
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("x-name")
export class XName extends LitElement {
  @state()
  name = "张三";

  render() {
    return html`<h1>你好 ${this.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>;
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("x-name")
export class XName extends LitElement {
  @state()
  name = "张三";

  constructor() {
    super();
    this.name = "李四";
  }

  render() {
    return html`<h1>你好 ${this.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>;
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("double-count")
export class DoubleCount extends LitElement {
  @state()
  count = 10;

  render() {
    const doubleCount = this.count * 2;
    return html`<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>;
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement } from "lit/decorators.js";

@customElement("hello-world")
export class HelloWorld extends LitElement {
  render() {
    return html`<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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html, css } from "lit";
import { customElement } from "lit/decorators.js";
import { styleMap } from "lit/directives/style-map.js";

@customElement("css-style")
export class CssStyle extends LitElement {
  static styles = css`
    .title {
      color: red;
    }
  `;

  render() {
    return html`
      <h1 class="title">我是红色的</h1>
      <button style=${styleMap({ fontSize: "10rem" })}>我是一个按钮</button>
    `;
  }
}

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>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement } from "lit/decorators.js";
import { repeat } from "lit/directives/repeat.js";

@customElement("colors-list")
export class ColorsList extends LitElement {
  colors = ["红", "绿", "蓝"];

  render() {
    return html`
      <ul>
        ${repeat(
          this.colors,
          (color) => color,
          (color) => html`<li>${color}</li>`,
        )}
      </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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("x-counter")
export class XCounter extends LitElement {
  @state()
  count = 0;

  incrementCount() {
    this.count = this.count + 1;
  }

  render() {
    return html`
      <p>计数器: ${this.count}</p>
      <button @click=${this.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} />;
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state, query } from "lit/decorators.js";

@customElement("input-focused")
export class InputFocused extends LitElement {
  @query("input") inputEl;

  firstUpdated() {
    this.inputEl.focus();
  }

  render() {
    return html`<input type="text" />`;
  }
}

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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";
import { choose } from "lit/directives/choose.js";

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

@customElement("traffic-light")
export class TrafficLight extends LitElement {
  @state()
  lightIndex = 0;

  get light() {
    return TRAFFIC_LIGHTS[this.lightIndex];
  }

  nextLight() {
    this.lightIndex = (this.lightIndex + 1) % TRAFFIC_LIGHTS.length;
  }

  render() {
    return html`
      <button @click=${this.nextLight}>下一个灯</button>
      <p>现在亮着的是: ${this.light}</p>
      <p>
        你应该
        ${choose(this.light, [
          ["红灯", () => html`<span>停下</span>`],
          ["黄灯", () => html`<span>慢行</span>`],
          ["绿灯", () => html`<span>赶紧走</span>`],
        ])}
      </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>;
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("page-title")
export class PageTitle extends LitElement {
  @state()
  pageTitle = "";

  connectedCallback() {
    super.connectedCallback();
    this.pageTitle = document.title;
  }

  render() {
    return html`<p>页面标题: ${this.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>;
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("x-time")
export class XTime extends LitElement {
  @state()
  time = "";

  timer;

  connectedCallback() {
    super.connectedCallback();
    this.timer = setInterval(() => {
      this.time = new Date().toLocaleTimeString();
    }, 1000);
  }

  disconnectedCallback() {
    super.disconnectedCallback();
    clearInterval(this.timer);
  }

  render() {
    return html`<p>当前时间: ${this.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
    />
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement } from "lit/decorators.js";

import "./user-profile";

@customElement("x-app")
export class XApp extends LitElement {
  render() {
    return html`<user-profile
      name="张三"
      age="20"
      .favouriteColors=${["green", "blue", "red"]}
      isAvailable
    ></user-profile>`;
  }
}

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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

import "./answer-button";

@customElement("x-app")
export class XApp extends LitElement {
  @state()
  isHappy = true;

  onAnswerNo() {
    this.isHappy = false;
  }

  onAnswerYes() {
    this.isHappy = true;
  }

  render() {
    return html`
      <p>你快乐吗?</p>
      <answer-button
        @yes=${this.onAnswerYes}
        @no=${this.onAnswerNo}
      ></answer-button>
      <p style="font-size: 50px;">${this.isHappy ? "😀" : "😥"}</p>
    `;
  }
}

slot插槽

React 标志 React

import FunnyButton from "./FunnyButton.jsx";

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

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement } from "lit/decorators.js";

import "./funny-button";

@customElement("x-app")
export class XApp extends LitElement {
  render() {
    return html`<funny-button>点我!</funny-button>`;
  }
}

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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement } from "lit/decorators.js";

import "./funny-button";

@customElement("x-app")
export class XApp extends LitElement {
  render() {
    return html`
      <funny-button></funny-button>
      <funny-button>这是传到slot的内容!</funny-button>
    `;
  }
}

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: "[email protected]",
  });

  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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";
import { ContextProvider } from "@lit/context";

import { userContext } from "./user-context";

import "./user-profile";

@customElement("x-app")
export class XApp extends LitElement {
  @state()
  user = {
    id: 1,
    username: "abcdefg",
    email: "[email protected]",
  };

  provider = new ContextProvider(this, {
    context: userContext,
    initialValue: this.user,
  });

  updateUsername(newUsername) {
    this.user = { ...this.user, username: newUsername };
    this.provider.setValue(this.user);
  }

  render() {
    return html` <h1>欢迎回来, ${this.user.username}</h1>
      <user-profile
        .user="${this.user}"
        .updateUsername=${this.updateUsername.bind(this)}
      ></user-profile>`;
  }
}

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} />
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("input-hello")
export class InputHello extends LitElement {
  @state()
  text = "你好世界";

  handleInput(event) {
    this.text = event.target.value;
  }

  render() {
    return html`
      <p>${this.text}</p>
      <input value=${this.text} @input=${this.handleInput} />
    `;
  }
}

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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("is-available")
export class IsAvailable extends LitElement {
  @state()
  isAvailable = false;

  handleChange() {
    this.isAvailable = !this.isAvailable;
  }

  render() {
    return html`
      <input
        id="is-available"
        type="checkbox"
        ?checked=${this.isAvailable}
        @change=${this.handleChange}
      />
      <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>
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";

@customElement("pick-pill")
export class PickPill extends LitElement {
  @state()
  picked = "red";

  handleChange(event) {
    this.picked = event.target.value;
  }

  render() {
    return html`
      <div>你选择了: ${this.picked}</div>

      <input
        id="blue-pill"
        name="pill"
        ?checked=${this.picked === "blue"}
        type="radio"
        value="blue"
        @change=${this.handleChange}
      />
      <label for="blue-pill">蓝色</label>

      <input
        id="red-pill"
        name="pill"
        ?checked=${this.picked === "red"}
        type="radio"
        value="red"
        @change=${this.handleChange}
      />
      <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>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement, state } from "lit/decorators.js";
import { repeat } from "lit/directives/repeat";

@customElement("color-select")
export class ColorSelect extends LitElement {
  colors = [
    { id: 1, text: "红" },
    { id: 2, text: "蓝" },
    { id: 3, text: "绿" },
    { id: 4, text: "灰", isDisabled: true },
  ];

  @state()
  selectedColorId = 2;

  handleChange(event) {
    this.selectedColorId = event.target.value;
  }

  render() {
    return html`
      <select @change=${this.handleChange}>
        ${repeat(
          this.colors,
          (color) => color.id,
          (color) =>
            html`<option
              value=${color.id}
              ?selected=${this.selectedColorId === color.id}
              ?disabled=${color.isDisabled}
            >
              ${color.text}
            </option>`,
        )}
      </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>

Lit 标志 Lit

<!doctype html>
<html>
  <head>
    <script type="module" src="./app.js"></script>
  </head>

  <body>
    <x-app />
  </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>
        )
      )}
    </>
  );
}

Lit 标志 Lit

import { LitElement, html } from "lit";
import { customElement } from "lit/decorators.js";
import { createFetchUsersTask } from "./fetch-users-task";

@customElement("x-app")
export class XApp extends LitElement {
  fetchUsers = createFetchUsersTask(this);

  render() {
    return this.fetchUsers.render({
      pending: () => html`<p>正在获取用户信息……</p>`,
      error: (e) => html`<p>获取用户信息出错</p>`,
      complete: (data) => html`
        <ul>
          ${data.map(
            (user) => html`
              <li>
                <img src=${user.picture.thumbnail} alt="user" />
                <p>${user.name.first} ${user.name.last}</p>
              </li>
            `,
          )}
        </ul>
      `,
    });
  }
}