Lit vs Alpine - JavaScript 框架语法对比

响应式

声明状态

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>`;
  }
}

Alpine

<h1 x-data="{ name: '张三' }" x-text="name"></h1>

更新状态

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>`;
  }
}

Alpine

<h1 x-data="{ name: '张三' }" x-init="name = '李四'" x-text="name"></h1>

计算属性

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>`;
  }
}

Alpine

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

模板语法

最简模板

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>`;
  }
}

Alpine

<h1>你好，世界</h1>

样式

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>
    `;
  }
}

Alpine

<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

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>
    `;
  }
}

Alpine

<ul x-data="{ colors: ['红', '绿', '蓝'] }">
  <template x-for="color in colors">
    <li x-text="color"></li>
  </template>
</ul>

点击事件

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>
    `;
  }
}

Alpine

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

DOM引用

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" />`;
  }
}

Alpine

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

条件渲染

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>
    `;
  }
}

Alpine

<div
  x-data="{
  TRAFFIC_LIGHTS: ['红灯', '黄灯', '绿灯'],
  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">下一个灯</button>
  <p>现在亮着的是: <span x-text="light"></span></p>
  <p>
    你应该
    <span x-show="light === '红灯'">停下</span>
    <span x-show="light === '黄灯'">慢行</span>
    <span x-show="light === '绿灯'">赶紧走</span>
  </p>
</div>

生命周期

组件加载时

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>`;
  }
}

Alpine

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

组件卸载时

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>`;
  }
}

Alpine

<p
  x-data="{
  time: new Date().toLocaleTimeString(),
  timer: null,
  init() { this.timer = setInterval(() => (this.time = new Date().toLocaleTimeString()), 1000) },
  destroy() { clearInterval(this.timer) }
}"
>
  当前时间: <span x-text="time"></span>
</p>

组件组合

组件Props传参

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>`;
  }
}

Alpine

<!--Alpine JS suggests using a server-side templating engine or another frontend framework in conjunction with Alpine to do this-->

<div
  x-data="{
  name: '张三',
  age: 20,
  favouriteColors: ['green', 'blue', 'red'],
  isAvailable: true
}"
>
  <p>我的名字是 <span x-text="张三"></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>

向父组件emit事件

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>
    `;
  }
}

Alpine

<div
  x-data="{ isHappy: true }"
  x-on:yes="isHappy = true"
  x-on:no="isHappy = false"
>
  <p>你快乐吗?</p>
  <div>
    <button x-on:click="$dispatch('yes')">是的！</button>
    <button x-on:click="$dispatch('no')">不是！</button>
  </div>
  <p style="font-size: 50px" x-text="isHappy ? '😀' : '😥'"></p>
</div>

slot插槽

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>`;
  }
}

Alpine

<!--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="'点我!'"
  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>默认slot内容</span>
</button>

slot插槽内容

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>
    `;
  }
}

Alpine

<!--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>默认slot内容</span>
</button>

<button
  x-data
  x-text="'这是传到slot的内容!'"
  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>默认slot内容</span>
</button>

上下文

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>`;
  }
}

Alpine

<!-- x-text 必须用在带有 x-data 的元素或其子元素上。 -->
<!-- 这两个元素可以共用一个带有 x-data 的父元素，也可以像下面这样分别添加 x-data： -->

<h1 x-data>
  欢迎回来, <span x-text="$store.user.username">未知用户</span>
</h1>

<div x-data>
  <h2>我的简介</h2>
  <p>用户名: <span x-text="$store.user.username"></span></p>
  <p>邮箱: <span x-text="$store.user.email"></span></p>
  <button @click="$store.user.updateUsername('李四')">
    更新用户名为 李四
  </button>
</div>

<script>
  document.addEventListener("alpine:init", () => {
    Alpine.store("user", {
      id: 1,
      username: "abcdefg",
      email: "[email protected]",

      updateUsername(newUsername) {
        this.username = newUsername;
      },
    });
  });
</script>

表单输入

输入框

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} />
    `;
  }
}

Alpine

<div x-data="{ text: '你好世界' }">
  <p x-text="text"></p>
  <input x-model="text" />
</div>

复选框

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>
    `;
  }
}

Alpine

<div x-data="{ isAvailable: true }">
  <input id="is-available" x-model="isAvailable" type="checkbox" />
  <label for="is-available">这是一个checkbox</label>
</div>

单选框

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>
    `;
  }
}

Alpine

<div x-data="{ picked: 'red' }">
  <div>你选择了: <span x-text="picked"></span></div>

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

  <input id="red-pill" x-model="picked" type="radio" value="red" />
  <label for="red-pill">红色</label>
</div>

选择器

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>
    `;
  }
}

Alpine

<div
  x-data="{
  selectedColorId: 2,
  colors: [
    { id: 1, text: '红' },
    { id: 2, text: '蓝' },
    { id: 3, text: '绿' },
    { id: 4, text: '灰', 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>

Web应用特性

渲染应用

Lit

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

  <body>
    <x-app />
  </body>
</html>

Alpine

<h1>你好，世界</h1>

fetch获取数据

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>
      `,
    });
  }
}

Alpine

<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>正在获取用户信息……</p>
  </template>

  <template x-if="error">
    <p>获取用户信息出错</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>

响应式 #

声明状态 #

Lit

Alpine

更新状态 #

Lit

Alpine

计算属性 #

Lit

Alpine

模板语法 #

最简模板 #

Lit

Alpine

样式 #

Lit

Alpine

DOM循环 #

Lit

Alpine

点击事件 #

Lit

Alpine

DOM引用 #

Lit

Alpine

条件渲染 #

Lit

Alpine

生命周期 #

组件加载时 #

Lit

Alpine

组件卸载时 #

Lit

Alpine

组件组合 #

组件Props传参 #

Lit

Alpine

向父组件emit事件 #

Lit

Alpine

slot插槽 #

Lit

Alpine

slot插槽内容 #

Lit

Alpine

上下文 #

Lit

Alpine

表单输入 #

输入框 #

Lit

Alpine

复选框 #

Lit

Alpine

单选框 #

Lit

Alpine

选择器 #

Lit

Alpine

Web应用特性 #

渲染应用 #

Lit

Alpine

fetch获取数据 #

Lit

Alpine

响应式

声明状态

更新状态

计算属性

模板语法

最简模板

样式

DOM循环

点击事件

DOM引用

条件渲染

生命周期

组件加载时

组件卸载时

组件组合

组件Props传参

向父组件emit事件

slot插槽

slot插槽内容

上下文

表单输入

输入框

复选框

单选框

选择器

Web应用特性

渲染应用

fetch获取数据