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Persistence with localStorage

中級~30 0/4 ステップ

Keep the ledger after refresh

Browser memory disappears when a page reloads. localStorage gives a small local-first application durable storage on the same device. Arrays must be serialized to JSON when saved and parsed when loaded.

Parsing can fail if stored data is damaged, so recovery is part of the feature—not an afterthought.

手順

1

Create loadTransactions with localStorage.getItem and JSON.parse.

ヒント: Read STORAGE_KEY, then parse only when raw exists.

2

Recover safely with try/catch and return an empty array on failure.

3

Create saveTransactions(items) with JSON.stringify.

4

Save after every push and render once on startup.

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