React #15 - Key - why key is required to iterate the list (Stop unnecessary re-render the list)
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In React, keys are essential when rendering lists because they help React identify which items have changed, been added, or removed. Here are the main reasons why keys are important:
1.) Efficient Updates: Keys help React efficiently update the DOM by identifying which elements need to be re-rendered. Without keys, React would have to re-render the entire list, which can be inefficient.
2.) Stable Identity: Keys provide a stable identity to each element in the list. This is crucial for maintaining the state of each element correctly. For example, if you have a list of items with input fields, using keys ensures that the input values are preserved correctly when the list changes.
3.) Avoiding Bugs: Without keys, React might mix up elements and their states, leading to bugs. For instance, if you reorder a list, React might not correctly associate the state of each item with its new position.
4.) Reconciliation: During the reconciliation process, React uses keys to match elements in the previous render with elements in the next render. This helps React determine the minimum number of changes needed to update the UI.