LESSON 2.3
Keys and list reconciliation
Learn key techniques and workflows in React Performance Engineering.
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Overview
Keys tell React which item is which. Using an array index means insertions silently reassign state to the wrong row.
In this lesson you will:
- Use stable identity for keys, never the array index
- Understand how reconciliation matches elements between renders
- Diagnose lost input state in a reordered list
Pro Tip
Use caching and revalidation wisely to ensure your app stays fast and data remains fresh without unnecessary requests.