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Validation and error handling

中級~30 0/4 ステップ

Protect the ledger from bad input

Real users mistype, paste spaces, and leave fields empty. Production code treats that as expected behavior. A validation function either returns a clean transaction or throws a precise error. The submit handler catches it and shows a useful message.

Never silently turn invalid money into zero. Invalid is not empty, and empty is not zero.

手順

1

Create createTransaction(description, amount) and trim the description.

ヒント: const cleanDescription = description.trim();

2

Reject a short description and non-positive or non-finite amount.

3

Wrap transaction creation in try/catch.

4

Show the error message in #form-error.

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