Edge Apps library 1.4.0: Edge Apps can keep showing the last good data when a fetch fails

Sat, 01 Aug 2026 00:00:00 +0000

A weather app on a lobby screen that loses its API for 10 minutes has 2 choices: show an error to everyone walking past, or keep showing the last forecast it had. writeEdgeAppCache() and readEdgeAppCache() make the second one a few lines of code:

import {
 getSettingWithDefault,
 readEdgeAppCache,
 writeEdgeAppCache,
} from '@screenly/edge-apps'

async function loadWeather() {
 try {
 const response = await fetch(weatherApiUrl)
 if (!response.ok) throw new Error(`Weather API returned ${response.status}`)

 const weather = await response.json()
 writeEdgeAppCache('weather-app', 'forecast', weather)
 return weather
 } catch (error) {
 if (getSettingWithDefault('display_errors', false)) throw error
 return readEdgeAppCache('weather-app', 'forecast')
 }
}

Values are stored in the player’s localStorage as JSON under namespace:key, so 2 apps, or 2 caches in one app, don’t overwrite each other. Anything JSON can hold works as a value.

The cache is for fallback, not freshness. Nothing expires, so read it only after a real failure, and expect it to be empty after the player restarts. Both functions fail quietly: readEdgeAppCache() returns null when there’s nothing usable, and writeEdgeAppCache() does nothing when storage is full or unavailable, so neither needs its own try.

Edge Apps library 1.4.0 | Screenly

Edge Apps library 1.4.0: Edge Apps can keep showing the last good data when a fetch fails