Thermostat Demo

This demo illustrates how to do cross-browser realtime update.

The state is globally shared (for all connections) and the logic is maintained on the server.

In addition, the document title is dynamically generated and updated in realtime.

Interactive UIs

Target: 21.5°
21.5°
idle
Source Code of thermostat.tsx
(import statements omitted for simplicity, click to expand)
import { Link } from '../components/router.js'
import { Style } from '../components/style.js'
import { o } from '../jsx/jsx.js'
import { sessions } from '../session.js'
import { Update, UpdateIn } from '../components/update.js'
import type { ServerMessage } from '../../../client/types'
import SourceCode from '../components/source-code.js'
import { Routes, StaticPageRoute } from '../routes.js'
import type { Node } from '../jsx/types'
import { apiEndpointTitle, title } from '../../config.js'
import { Locale, isPreferZh } from '../components/locale.js'
import { Context, DynamicContext } from '../context.js'
const UpdateInterval = 1000

type Status = 'cooling' | 'heating' | 'idle'

const StatusStyles: Record<Status, string> = {
  heating: `
background: #f83;
background: linear-gradient(180deg, #f83 0%, #f54 100%);
color: white;
`.replace(/\n/g, ' '),
  cooling: `
background: #6ae;
background: linear-gradient(180deg, #6ae 0%, #17d 100%);
color: white;
`.replace(/\n/g, ' '),
  idle: `
background: #eef;
background: radial-gradient(#fff 0%, #eef 100%);
color: black;
`.replace(/\n/g, ' '),
}

class State {
  private _current = 27
  private _target = 25.5
  private _status: Status = 'idle'
  private tick = () => {
    if (this.current === this.target) {
      this.status = 'idle'
      this.timer = null
      return
    }
    if (this.current > this.target) {
      this.status = 'cooling'
      this.current -= 0.5
    } else if (this.current < this.target) {
      this.status = 'heating'
      this.current += 0.5
    }
    this.timer = setTimeout(this.tick, UpdateInterval)
  }
  private timer: NodeJS.Timeout | null = setTimeout(this.tick)
  get status() {
    return this._status
  }
  set status(value: Status) {
    if (this._status === value) return
    this._status = value
    let messages: ServerMessage[] = [
      ['update-in', '#thermostat #status', value, this.title],
      [
        'update-attrs',
        '#thermostat .outer.circle',
        {
          style: StatusStyles[value],
        },
      ],
    ]
    update(['batch', messages])
  }
  get target() {
    return this._target
  }
  set target(value: number) {
    if (this._target === value) return
    this._target = value
    update(['update-in', '#thermostat #target', value.toFixed(1), this.title])
    if (!this.timer) {
      this.timer = setTimeout(this.tick)
    }
  }
  get current() {
    return this._current
  }
  set current(value: number) {
    if (this._current === value) return
    this._current = value
    update(['update-in', '#thermostat #current', value.toFixed(1), this.title])
  }
  get targetText() {
    return this.target.toFixed(1) + '°'
  }
  get currentText() {
    return this.current.toFixed(1) + '°'
  }
  get title() {
    return title(`C: ${this.currentText} | T: ${this.targetText} | Thermostat`)
  }
}
const state = new State()

function inc() {
  state.target += 0.5
  return (
    <UpdateIn
      to="/thermostat"
      selector="#thermostat #target"
      content={state.target.toFixed(1)}
      title={state.title}
    />
  )
}

function dec() {
  state.target -= 0.5
  return (
    <UpdateIn
      to="/thermostat"
      selector="#thermostat #target"
      content={state.target.toFixed(1)}
      title={state.title}
    />
  )
}

function update(message: ServerMessage) {
  sessions.forEach(session => {
    if (session.url === '/thermostat') {
      session.ws.send(message)
    }
  })
  return <Update to="/thermostat" message={message} />
}

/* the root node is statically built at boot-time (doesn't need to be reconstructed at request-time) */
let Thermostat: Node = (
  <div id="thermostat">
    {Style(/* css */ `
#thermostat button {
  margin: 0.25em;
  font-size: larger;
}
#thermostat [data-live=redirect] {
  display: block;
}
#thermostat .title {
  width: min(72vw,72vh);
  text-align: center;
}
#thermostat .circle.outer {
  --size: min(72vw,72vh);
  background-color: #eef;
  display: flex;
  flex-direction: column;
  justify-content: center;
}
#thermostat .circle.outer > div {
  display: flex;
  flex-direction: row;
  justify-content: center;
}
#thermostat .circle.outer > .text-container {
  font-size: 1.25em;
  padding: min(3vw,3vh);
}
#thermostat .circle.middle {
  --size: min(48vw,48vh);
  display: flex;
  flex-direction: row;
  justify-content: center;
  background-color: #eee;
  color: black;
}
#thermostat .circle.middle > div {
  display: flex;
  flex-direction: column;
  justify-content: center;
}
#thermostat .circle.middle button {
  border: none;
  width: min(12vw,12vh);
  height: min(12vw,12vh);
  margin: 0;
  background-color: transparent;
  font-size: 2em;
  cursor: pointer;
}
#thermostat .circle.middle button:hover {
  outline: 1px solid gray;
}
#thermostat .circle.inner {
  --size: min(24vw,24vh);
  background-color: white;
  display: flex;
  flex-direction: column;
  text-align: center;
  justify-content: center;
  font-size: 1.6em;
}
#thermostat .circle {
  border-radius: 100%;
  border: 1px solid black;
  width: var(--size);
  height: var(--size);
}
`)}
    <h1>
      <Locale en="Thermostat Demo" zh="溫控器範例" />
    </h1>
    <p>
      <Locale
        en="This demo illustrates how to do cross-browser realtime update."
        zh="此範例展示了如何實現跨瀏覽器的即時更新。"
      />
    </p>
    <p>
      <Locale
        en="The state is globally shared (for all connections) and the logic is maintained on the server."
        zh="狀態在所有連線中是全域共享的,邏輯由伺服器維護。"
      />
    </p>
    <p>
      <Locale
        en="In addition, the document title is dynamically generated and updated in realtime."
        zh="此外,文件標題是動態生成並即時更新的。"
      />
    </p>
    <h2 class="title">
      <Locale en="Interactive UIs" zh="互動式介面" />
    </h2>
    <div class="outer circle" style={StatusStyles[state.status]}>
      <div class="text-container">
        <Locale en="Target:" zh="目標溫度:" />
        &nbsp;
        <span
          title={
            <Locale
              en="Target temperature in celsius degree"
              zh="攝氏目標溫度"
            />
          }
        >
          <span id="target">
            {
              /* this fraction is wrapped in an inline functional component to evaluate the state at request-time */
              [() => state.target.toFixed(1)]
            }
          </span>
          &deg;
        </span>
      </div>
      <div>
        <div class="middle circle">
          <div>
            <Link
              href="/thermostat/dec"
              no-history
              title={
                <Locale
                  en="Reduce target temperature by 0.5 celsius degree"
                  zh="降低目標溫度0.5攝氏度"
                />
              }
            >
              <button>-</button>
            </Link>
          </div>
          <div>
            <div class="inner circle">
              <span
                title={
                  <Locale
                    en="Current temperature in celsius degree"
                    zh="當前攝氏溫度"
                  />
                }
              >
                <span id="current">{[() => state.current.toFixed(1)]}</span>
                &deg;
              </span>
            </div>
          </div>
          <div>
            <Link
              href="/thermostat/inc"
              no-history
              title={
                <Locale
                  en="Increase target temperature by 0.5 celsius degree"
                  zh="增加目標溫度0.5攝氏度"
                />
              }
            >
              <button>+</button>
            </Link>
          </div>
        </div>
      </div>
      <div class="text-container">
        <span id="status" title={<Locale en="Current status" zh="當前狀態" />}>
          {[() => state.status]}
        </span>
      </div>
    </div>
    <SourceCode page="thermostat.tsx" />
    <p>
      <a href="https://dockyard.com/blog/2018/12/12/phoenix-liveview-interactive-real-time-apps-no-need-to-write-javascript">
        <Locale en="Layout reference" zh="界面參考" />
      </a>
    </p>
  </div>
)

function index(context: Context): StaticPageRoute {
  let zh = isPreferZh(context)
  return {
    title: zh ? '溫控器範例' : 'Thermostat Demo',
    description: zh
      ? `一個即時更新的溫控器範例應用程式。當前溫度:${state.currentText};目標溫度:${state.targetText}。`
      : `A real-time updated thermostat demo application. Current temperature: ${state.currentText}; target temperature: ${state.targetText}.`,
    node: Thermostat,
  }
}

let routes = {
  '/thermostat': {
    menuText: <Locale en="Thermostat" zh="溫控器" />,
    resolve: index,
  },
  '/thermostat/inc': {
    title: apiEndpointTitle,
    description: 'increase target temperature of the demo thermostat',
    node: [inc],
    streaming: false,
  },
  '/thermostat/dec': {
    title: apiEndpointTitle,
    description: 'decrease target temperature of the demo thermostat',
    node: [dec],
    streaming: false,
  },
} satisfies Routes

export default { routes }

Layout reference