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Component Party

Reactivity

Declare state

logo of Lit Lit

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

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

  render() {
    return html`<h1>Hello ${this.name}!</h1>`;
  }
}

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import { track } from "ripple";

export default function Name() {
  let &[name] = track("John");

  return <h1>"Hello "{name}</h1>;
}

Update state

logo of Lit Lit

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

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

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

  render() {
    return html`<h1>Hello ${this.name}!</h1>`;
  }
}

logo of Ripple Ripple

import { track } from "ripple";

export default function Name() {
  let &[name] = track("John");
  name = "Jane";

  return <h1>"Hello "{name}</h1>;
}

Computed state

logo of Lit 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>`;
  }
}

logo of Ripple Ripple

import { track } from "ripple";

export default function DoubleCount() {
  let &[count] = track(10);
  let &[doubleCount] = track(() => count * 2);

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

Templating

Minimal template

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

@customElement("hello-world")
export class HelloWorld extends LitElement {
  render() {
    return html`<h1>Hello world</h1>`;
  }
}

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export default function HelloWorld() {
  return <h1>"Hello world"</h1>;
}

Styling

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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">I am red</h1>
      <button style=${styleMap({ fontSize: "10rem" })}>I am a button</button>
    `;
  }
}

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export default function CssStyle() {
  return <>
    <h1 class="title">"I am red"</h1>
    <button style={{ fontSize: "10rem" }}>"I am a button"</button>

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

Loop

logo of Lit 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 = ["red", "green", "blue"];

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

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export default function Colors() {
  const colors = ["red", "green", "blue"];

  return <ul>
    for (const color of colors; key color) {
      <li>{color}</li>
    }
  </ul>;
}

Event click

logo of Lit 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>Counter: ${this.count}</p>
      <button @click=${this.incrementCount}>+1</button>
    `;
  }
}

logo of Ripple Ripple

import { track } from "ripple";

export default function Counter() {
  let &[count] = track(0);

  function incrementCount() {
    count++;
  }

  return <>
    <p>"Count: "{count}</p>
    <button onClick={incrementCount}>"+1"</button>
  </>;
}

Dom ref

logo of Lit 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" />`;
  }
}

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export default function InputFocused() {
  function autofocus(element) {
    element.focus();
  }

  return <input ref={autofocus} />;
}

Conditional

logo of Lit Lit

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

const TRAFFIC_LIGHTS = ["red", "orange", "green"];

@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}>Next light</button>
      <p>Light is ${this.light}</p>
      <p>
        You must
        ${choose(this.light, [
          ["red", () => html`<span>STOP</span>`],
          ["orange", () => html`<span>SLOW DOWN</span>`],
          ["green", () => html`<span>GO</span>`],
        ])}
      </p>
    `;
  }
}

logo of Ripple Ripple

import { track } from "ripple";

const TRAFFIC_LIGHTS = ["red", "orange", "green"];

export default function TrafficLight() {
  let &[lightIndex] = track(0);

  let &[light] = track(() => TRAFFIC_LIGHTS[lightIndex]);

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

  return <>
    <button onClick={nextLight}>"Next light"</button>
    <p>"Light is "{light}</p>
    <p>
      "You must "
      if (light === "red") {
        <span>"STOP"</span>
      } else if (light === "orange") {
        <span>"SLOW DOWN"</span>
      } else if (light === "green") {
        <span>"GO"</span>
      }
    </p>
  </>;
}

Lifecycle

On mount

logo of Lit 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>Page title: ${this.pageTitle}</p>`;
  }
}

logo of Ripple Ripple

import { effect, track } from "ripple";

export default function PageTitle() {
  let &[pageTitle] = track("");

  effect(() => {
    pageTitle = document.title;
  });

  return <h1>"Page title: "{pageTitle}</h1>;
}

On unmount

logo of Lit 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>Current time: ${this.time}</p>`;
  }
}

logo of Ripple Ripple

import { effect, track } from "ripple";

export default function Time() {
  let &[time] = track(new Date().toLocaleTimeString());

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

    return () => clearInterval(timer);
  });

  return <h1>"Current time: "{time}</h1>;
}

Component composition

Props

logo of Lit 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="John"
      age="20"
      .favouriteColors=${["green", "blue", "red"]}
      isAvailable
    ></user-profile>`;
  }
}

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import { UserProfile } from "./UserProfile.tsrx";

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

Emit to parent

logo of Lit 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>Are you happy?</p>
      <answer-button
        @yes=${this.onAnswerYes}
        @no=${this.onAnswerNo}
      ></answer-button>
      <p style="font-size: 50px;">${this.isHappy ? "😀" : "😥"}</p>
    `;
  }
}

logo of Ripple Ripple

import { track } from "ripple";

import { AnswerButton } from "./AnswerButton.tsrx";

export function App() {
  let &[isHappy] = track(true);

  function onAnswerNo() {
    isHappy = false;
  }

  function onAnswerYes() {
    isHappy = true;
  }

  return <>
    <p>"Are you happy?"</p>
    <AnswerButton onYes={onAnswerYes} onNo={onAnswerNo} />
    <p style={{ fontSize: "50px" }}>{isHappy ? "😀" : "😥"}</p>
  </>;
}

Slot

logo of Lit 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>Click me!</funny-button>`;
  }
}

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import { FunnyButton } from "./FunnyButton.tsrx";

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

Slot fallback

logo of Lit 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>Click me!</funny-button>
    `;
  }
}

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import { FunnyButton } from "./FunnyButton.tsrx";

export function App() {
  return <>
    <FunnyButton />
    <FunnyButton>"I got content!"</FunnyButton>
  </>;
}

Context

logo of Lit 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: "unicorn42",
    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>Welcome back, ${this.user.username}</h1>
      <user-profile
        .user="${this.user}"
        .updateUsername=${this.updateUsername.bind(this)}
      ></user-profile>`;
  }
}

logo of Ripple Ripple

import { RippleObject } from "ripple";

import { UserContext } from "./UserContext.tsrx";
import { UserProfile } from "./UserProfile.tsrx";

export function App() {
  const user = new RippleObject({
    id: 1,
    username: "unicorn42",
    email: "[email protected]",
  });

  UserContext.set(user);

  return <>
    <h1>"Welcome back, "{user.username}</h1>
    <UserProfile />
  </>;
}

Form input

Input text

logo of Lit Lit

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

@customElement("input-hello")
export class InputHello extends LitElement {
  @state()
  text = "Hello World";

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

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

logo of Ripple Ripple

import { bindValue, track } from "ripple";

export default function InputHello() {
  let &[text, textTracked] = track("Hello world");

  return <>
    <p>{text}</p>
    <input ref={bindValue(textTracked)} />
  </>;
}

Checkbox

logo of Lit 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">Is available</label>
    `;
  }
}

logo of Ripple Ripple

import { bindChecked, track } from "ripple";

export default function IsAvailable() {
  let &[isAvailable, isAvailableTracked] = track(false);

  return <>
    <input
      id="is-available"
      type="checkbox"
      ref={bindChecked(isAvailableTracked)}
    />
    <label for="is-available">"Is available"</label>
  </>;
}

Radio

logo of Lit 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>Picked: ${this.picked}</div>

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

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

logo of Ripple Ripple

import { bindGroup, track } from "ripple";

export default function PickPill() {
  let &[picked, pickedTracked] = track("red");

  return <>
    <div>"Picked: "{picked}</div>

    <input
      id="blue-pill"
      type="radio"
      value="blue"
      ref={bindGroup(pickedTracked)}
    />
    <label for="blue-pill">"Blue pill"</label>

    <input
      id="red-pill"
      type="radio"
      value="red"
      ref={bindGroup(pickedTracked)}
    />
    <label for="red-pill">"Red pill"</label>
  </>;
}

Select

logo of Lit 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: "red" },
    { id: 2, text: "blue" },
    { id: 3, text: "green" },
    { id: 4, text: "gray", 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>
    `;
  }
}

logo of Ripple Ripple

import { bindValue, track } from "ripple";

const colors = [
  { id: 1, text: "red" },
  { id: 2, text: "blue" },
  { id: 3, text: "green" },
  { id: 4, text: "gray", isDisabled: true },
];

export default function ColorSelect() {
  let &[selectedColorId, selectedColorIdTracked] = track(2);

  return <select ref={bindValue(selectedColorIdTracked)}>
    for (const color of colors; key color.id) {
      <option value={color.id} disabled={color.isDisabled}>
        {color.text}
      </option>
    }
  </select>;
}

Webapp features

Render app

logo of Lit Lit

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

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

logo of Ripple Ripple

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

Fetch data

logo of Lit 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>Fetching users...</p>`,
      error: (e) => html`<p>An error occurred while fetching users</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>
      `,
    });
  }
}

logo of Ripple Ripple

import { useFetchUsers } from "./useFetchUsers.tsrx";

export function App() {
  const data = useFetchUsers();

  return <>
    if (data.isLoading) {
      <p>"Fetching users..."</p>
    } else if (data.error) {
      <p>"An error occurred while fetching users"</p>
    } else if (data.users) {
      <ul>
        for (const user of data.users; key user.login.uuid) {
          <li>
            <img src={user.picture.thumbnail} alt="user" />
            <p>{user.name.first}" "{user.name.last}</p>
          </li>
        }
      </ul>
    }
  </>;
}