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memo() vs. useMemo()

pra's play answered on September 5, 2024 Popularity 1/10 Helpfulness 1/10

answer memo() vs. useMemo()

memo() vs. useMemo()

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`memo()` vs. `useMemo()` in React: A Comparison

Both `memo()` and `useMemo()` are optimization techniques in React that help prevent unnecessary re-renders, but they serve slightly different purposes:

`React.memo()`

* Purpose: Prevents unnecessary re-renders of functional components based on prop changes.
* How it works: Memoizes the component's result and only re-renders it if its props have changed.
* Use case: Optimizing components that are expensive to render and don't need to re-render unless their props change.

Example:

```javascript
import React, { memo } from 'react';

const MyComponent = memo(({ name }) => {
  console.log('MyComponent rendered');
  return <div>{name}</div>;
});
```

`useMemo()`

* Purpose: Memoizes the result of an expensive function call within a component.
* How it works: Caches the result of the function and only re-calculates it if its dependencies have changed.
* Use case: Optimizing computationally expensive calculations within components.

Example:

```javascript
import React, { useMemo } from 'react';

const MyComponent = ({ data }) => {
  const expensiveCalculation = useMemo(() => {
    console.log('Expensive calculation performed');
    return data.reduce((acc, item) => acc + item.value, 0);
  }, [data]);

  return <div>{expensiveCalculation}</div>;
};
```

Key Differences:

- Target:`memo()` optimizes component re-renders, while `useMemo()` optimizes function calls.
- Dependencies:`memo()` uses prop equality for re-render checks, while `useMemo()` uses a dependency array for recalculation.
- Usage: `memo()` is typically used to wrap components, while `useMemo()` is used within components to memoize functions.

Choosing the Right Tool:

- Use `memo()` when you want to prevent a component from re-rendering unless its props change.
- Use `useMemo()` when you have expensive calculations within a component that you want to avoid re-computing unnecessarily.
- Remember to carefully consider the dependencies passed to both `memo()` and `useMemo()` to ensure they are optimized correctly.

Popularity 1/10 Helpfulness 1/10 Language javascript

Source: Grepper

Tags: javascript

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Contributed on Sep 05 2024

pra's play

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memo() vs. useMemo()

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