connect-api

Required reading

Before generating or modifying any code, read both:

• ${CLAUDE_PLUGIN_ROOT}/references/display-guidelines.md
• ${CLAUDE_PLUGIN_ROOT}/references/performance-guidelines.md

These define the non-negotiable display physics, input model, and performance budgets for Meta Display Glasses webapps. Do not skip — generated UI that ignores these will fail on-device.

Connect API to Meta Display Glasses WebApp

Add real API connections to an existing webapp. The base app.js template already includes apiGet(), setLoading(), setError(), showToast(), and connectWebSocket() helpers — this skill shows how to wire them up.

Prerequisites

• Existing webapp created via /create-webapp (which includes the API/UI helpers in app.js)

Steps

1. Gather Information

Ask the user:

• What data? What information should the app display?
• Which API? Specific API, or should we pick one?
• Refresh behavior? Manual, auto-refresh interval, or real-time WebSocket?
• Offline fallback? Should cached data be served when offline?

2. Choose an API

If not specified, recommend from these free, no-key-required APIs:

Category	API	Base URL
Weather	Open-Meteo	api.open-meteo.com/v1/forecast
Trivia	Open Trivia DB	opentdb.com/api.php
Crypto	CoinGecko	api.coingecko.com/api/v3
Earthquakes	USGS	earthquake.usgs.gov/earthquakes/feed/v1.0
Wikipedia	Wikipedia REST	en.wikipedia.org/api/rest_v1
Recipes	TheMealDB	themealdb.com/api/json/v1/1
Countries	REST Countries	restcountries.com/v3.1
Jokes	Official Joke API	official-joke-api.appspot.com
Pokemon	PokeAPI	pokeapi.co/api/v2
IP Location	ipapi	ipapi.co/json/

3. Add Loading and Error UI

Add these elements inside the relevant screen in index.html (the CSS is already in styles.css from /create-webapp):

<div id="loading" class="loading-container hidden">
  <div class="loading-spinner"></div>
  <div class="loading-text">Loading...</div>
</div>

<div id="error" class="error-container hidden">
  <div class="error-icon">&#9888;</div>
  <div class="error-message">Something went wrong</div>
  <button class="nav-item focusable" data-action="refresh">Try Again</button>
</div>

Add a refresh button to the nav bar:

<button class="nav-item focusable" data-action="refresh">&#8635; Refresh</button>

4. Update API Configuration

In app.js, update the CONFIG object:

api: {
  baseUrl: 'https://api.example.com',
  cacheDuration: 5 * 60 * 1000,
},

5. Add Data Fetching

Use the existing apiGet() helper in onScreenEnter():

function onScreenEnter(screenId) {
  switch (screenId) {
    case 'home':
      loadData();
      break;
  }
}

function loadData() {
  apiGet(CONFIG.api.baseUrl + '/endpoint', { cacheKey: 'my-data' })
    .then(function(data) {
      renderData(data);
    })
    .catch(function() {
      // Error already shown by apiGet
    });
}

6. Add Refresh Action

In handleAppAction():

case 'refresh':
  state.cache = {};
  onScreenEnter(state.currentScreen);
  break;

7. For WebSocket Connections

Use the existing connectWebSocket() helper:

var ws = connectWebSocket('wss://stream.example.com/data', {
  onOpen: function() { showToast('Connected', 'success'); },
  onMessage: function(data) { updateDisplay(data); },
  onClose: function() { showToast('Reconnecting...', 'warning'); },
  onError: function() { showToast('Connection error', 'error'); },
});

8. Add Auto-Refresh (Optional)

For periodic updates:

var refreshInterval = null;

function startAutoRefresh(intervalMs) {
  stopAutoRefresh();
  refreshInterval = setInterval(function() {
    onScreenEnter(state.currentScreen);
  }, intervalMs || 60000);
}

function stopAutoRefresh() {
  if (refreshInterval) {
    clearInterval(refreshInterval);
    refreshInterval = null;
  }
}

Start in init(): startAutoRefresh(60000);

Complete Examples

Weather API

function loadWeather() {
  var url = 'https://api.open-meteo.com/v1/forecast' +
    '?latitude=40.71&longitude=-74.01' +
    '&current_weather=true' +
    '&daily=temperature_2m_max,temperature_2m_min,weathercode' +
    '&timezone=auto&forecast_days=5';

  apiGet(url, { cacheKey: 'weather' })
    .then(function(data) {
      var w = data.current_weather;
      document.getElementById('temp').textContent = Math.round(w.temperature) + '\u00B0';
      document.getElementById('condition').textContent = getWeatherLabel(w.weathercode);
      document.getElementById('wind').textContent = w.windspeed + ' km/h';
      renderForecast(data.daily);
    });
}

Crypto Price Tracker

function loadPrices() {
  var url = 'https://api.coingecko.com/api/v3/simple/price' +
    '?ids=bitcoin,ethereum,solana' +
    '&vs_currencies=usd&include_24hr_change=true';

  apiGet(url, { cacheKey: 'crypto', cacheDuration: 30000 })
    .then(function(data) {
      Object.keys(data).forEach(function(coin) {
        var price = data[coin].usd;
        var change = data[coin].usd_24h_change;
        document.getElementById(coin + '-price').textContent = '$' + price.toLocaleString();
        var changeEl = document.getElementById(coin + '-change');
        changeEl.textContent = (change >= 0 ? '+' : '') + change.toFixed(2) + '%';
        changeEl.className = 'badge ' + (change >= 0 ? 'badge-success' : 'badge-danger');
      });
    });
}

Verify

• Loading spinner appears during API calls
• Error state appears on network failure
• Cached data is served on repeated loads
• Refresh button clears cache and fetches fresh data
• All API-rendered elements have .focusable class for D-pad navigation

Related Skills

• /add-ui — Add screens, buttons, and components for API data