Ole-Morten Duesund e8428de775 Add progressive web app companion for cross-platform access

Vite + TypeScript PWA that mirrors the Android app's core features:
- Pre-processed shelter data (build-time UTM33N→WGS84 conversion)
- Leaflet map with shelter markers, user location, and offline tiles
- Canvas compass arrow (ported from DirectionArrowView.kt)
- IndexedDB shelter cache with 7-day staleness check
- Service worker with CacheFirst tiles and precached app shell
- i18n for en, nb, nn (ported from Android strings.xml)
- iOS/Android compass handling with low-pass filter
- Respects user map interaction (no auto-snap on pan/zoom)
- Build revision cache-breaker for reliable SW updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2026-03-08 17:41:38 +01:00

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is-callable

Is this JS value callable? Works with Functions and GeneratorFunctions, despite ES6 @@toStringTag.

Supported engines

Automatically tested in every minor version of node.

Manually tested in:

Safari: v4 - v15 _{(4, 5, 5.1, 6.0.5, 6.2, 7.1, 8, 9.1.3, 10.1.2, 11.1.2, 12.1, 13.1.2, 14.1.2, 15.3, 15.6.1)}
- Note: Safari 9 has class, but Function.prototype.toString hides that progeny and makes them look like functions, so class constructors will be reported by this package as callable, when they are not in fact callable.
Chrome: v15 - v81, v83 - v106_{(every integer version)}
- Note: This includes Edge v80+ and Opera v15+, which matches Chrome
Firefox: v3, v3.6, v4 - v105 _{(every integer version)}
- Note: v45 - v54 has class, but Function.prototype.toString hides that progeny and makes them look like functions, so class constructors will be reported by this package as callable, when they are not in fact callable.
- Note: in v42 - v63, Function.prototype.toString throws on HTML element constructors, or a Proxy to a function
- Note: in v20 - v35, HTML element constructors are not callable, despite having typeof function.
- Note: in v19, document.all is not callable.
IE: v6 - v11_{(every integer version}
Opera: v11.1, v11.5, v11.6, v12.1, v12.14, v12.15, v12.16, v15+ _{v15+ matches Chrome}

Example

var isCallable = require('is-callable');
var assert = require('assert');

assert.notOk(isCallable(undefined));
assert.notOk(isCallable(null));
assert.notOk(isCallable(false));
assert.notOk(isCallable(true));
assert.notOk(isCallable([]));
assert.notOk(isCallable({}));
assert.notOk(isCallable(/a/g));
assert.notOk(isCallable(new RegExp('a', 'g')));
assert.notOk(isCallable(new Date()));
assert.notOk(isCallable(42));
assert.notOk(isCallable(NaN));
assert.notOk(isCallable(Infinity));
assert.notOk(isCallable(new Number(42)));
assert.notOk(isCallable('foo'));
assert.notOk(isCallable(Object('foo')));

assert.ok(isCallable(function () {}));
assert.ok(isCallable(function* () {}));
assert.ok(isCallable(x => x * x));

Install

Install with

npm install is-callable

Tests

Simply clone the repo, npm install, and run npm test

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