mirror of
https://github.com/kjanat/livedash-node.git
synced 2026-02-13 12:55:42 +01:00
Kaj Kowalski
cd05fc8648
- Fix syntax errors in skills markdown files (.github/skills, .opencode/skills) - Change typescript to tsx for code blocks with JSX - Replace ellipsis (...) in array examples with valid syntax - Separate CSS from TypeScript into distinct code blocks - Convert JavaScript object examples to valid JSON in docs - Fix enum definitions with proper comma separation
1.6 KiB
1.6 KiB
title, impact, impactDescription, tags
| title | impact | impactDescription | tags |
|---|---|---|---|
| Cache Storage API Calls | LOW-MEDIUM | reduces expensive I/O | javascript, localStorage, storage, caching, performance |
Cache Storage API Calls
localStorage, sessionStorage, and document.cookie are synchronous and expensive. Cache reads in memory.
Incorrect (reads storage on every call):
function getTheme() {
return localStorage.getItem("theme") ?? "light";
}
// Called 10 times = 10 storage reads
Correct (Map cache):
const storageCache = new Map<string, string | null>();
function getLocalStorage(key: string) {
if (!storageCache.has(key)) {
storageCache.set(key, localStorage.getItem(key));
}
return storageCache.get(key);
}
function setLocalStorage(key: string, value: string) {
localStorage.setItem(key, value);
storageCache.set(key, value); // keep cache in sync
}
Use a Map (not a hook) so it works everywhere: utilities, event handlers, not just React components.
Cookie caching:
let cookieCache: Record<string, string> | null = null;
function getCookie(name: string) {
if (!cookieCache) {
cookieCache = Object.fromEntries(document.cookie.split("; ").map((c) => c.split("=")));
}
return cookieCache[name];
}
Important (invalidate on external changes):
If storage can change externally (another tab, server-set cookies), invalidate cache:
window.addEventListener("storage", (e) => {
if (e.key) storageCache.delete(e.key);
});
document.addEventListener("visibilitychange", () => {
if (document.visibilityState === "visible") {
storageCache.clear();
}
});