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2 Answers

Nikita Biichuk

- answered 9 months ago

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0

In React, keys are important because they help React identify which items have changed or been added/removed in a list. This allows React to re-render only the items that have actually changed, which is more efficient than re-rendering the entire list.

When assigning keys to list items in React, there are a few guidelines you should follow:

1. Keys should be unique: Each key within a list should be unique among its siblings. This helps React correctly identify each item.

2. Keys should be stable: Avoid using random values as keys, as they can change between re-renders and lead to performance issues.

3. Avoid using array indexes as keys: While it might be tempting to use array indexes as keys, it is not recommended, especially when the list is dynamically modified (items added/removed).

John Doe

- answered 1 year ago

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0

In React, keys are important for optimizing re-rendering of lists of components. They help React identify which items have changed, are added, or are removed. Here are some guidelines on choosing keys for list items:

1. Keys should be unique: Ensure that each key is unique among siblings within the same list.

2. Use stable identities: Prefer using stable identities for keys. Using indexes as keys is discouraged as it can lead to performance issues and incorrect behavior.

3. Don't use random values: Avoid using random values as keys, as they can cause unnecessary re-renders.

4. Use unique identifiers: If your data has unique IDs, such as database IDs, use them as keys to ensure consistency.

5. Consider the list's stability: If the list order may change or items may be added/removed frequently, choose keys that are resilient to such changes.

Here's a simple example to illustrate using keys in a list of components in React:

const items = [
{ id: 1, name: 'Item 1' },
{ id: 2, name: 'Item 2' },
{ id: 3, name: 'Item 3' },
];

function MyComponent() {
return (
{items.map(item => (
{item.name}
))}
);
}

In this example, `item.id` is used as a key because it provides a stable identity for each item. This way, React can efficiently update the list when changes occur. Remember to apply these guidelines when choosing keys for your list items in React to ensure optimal performance and correct rendering behavior.

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