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Components · easy

7. Lists with FlatList

Efficiently rendering long, scrollable data.

1 min read3 questionsup to 50 XPtopic 7/50

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`FlatList` renders only the items currently visible (plus a small buffer), which is essential for a transaction history or an NFT gallery that could contain thousands of rows.

import { FlatList, Text } from "react-native";

function TxList({ txs }: { txs: { hash: string; amount: number }[] }) {
  return (
    <FlatList
      data={txs}
      keyExtractor={(tx) => tx.hash}
      renderItem={({ item }) => <Text>{item.hash}: {item.amount}</Text>}
    />
  );
}

`keyExtractor` must return a stable, unique id per item (a transaction hash is ideal); using the array index breaks state and animations when the list reorders.

How to study this topic

  1. 1. Read the explanation once end to end, skipping the code.
  2. 2. Re-read the code snippets and say out loud what each line does.
  3. 3. Answer the quiz without scrolling back — that is the real check.
  4. 4. Read every explanation, even for the answers you got right.

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Check your understanding

  1. 1. Why prefer FlatList over ScrollView for long lists?

  2. 2. What should keyExtractor return?

  3. 3. What prop supplies the array of items?

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