Created
May 18, 2024 08:49
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In memory caching to reduce data usage for frequent API requests, repeated data processing or similar use cases.
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| const FIVE_MINUTES = 1000 * 60 * 5 | |
| function createCache<K, V>({ maxAge }: { maxAge: number }) { | |
| const cache = new Map< | |
| K, | |
| V & { cachedAt: ReturnType<(typeof Date)['now']> } | |
| >() | |
| return { | |
| set(key: K, value: V) { | |
| cache.set(key, { ...value, cachedAt: Date.now() }) | |
| }, | |
| /** | |
| * Verify that the value both exists and that it's newer than `maxAge` | |
| */ | |
| has(key: K) { | |
| const value = cache.get(key) | |
| if (value && Date.now() - value.cachedAt < maxAge) { | |
| return true | |
| } | |
| return false | |
| }, | |
| get(key: K) { | |
| const value = cache.get(key) | |
| if (value) { | |
| // Make a copy with the actual data and delete internal caching details | |
| const dataOnly: V = { ...value } | |
| delete (dataOnly as V & { cachedAt?: number }).cachedAt | |
| return dataOnly | |
| } | |
| }, | |
| } | |
| } | |
| const cachedCases = createCache<Case['beteckning'], Case>({ | |
| maxAge: FIVE_MINUTES, | |
| }) |
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