Optimize React Component Performance with Memoization Using React.memo()
Tags: react, nextjs, programming, beginners
Published: 2023-02-17 10:32:21

In this article, we will discuss what the `React.memo()` function is, how it works, and when to use it in your React apps. Initiating our adventure..

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## **What is the React.memo() function?**
React components are programmed to re-render upon the modification of state or props value. Although, this feature may hamper your app's performance as it causes all child components associated with the parent component to also re-render, even if the alteration was meant only for the parent component. The parent component's re-rendering triggers the re-rendering of all its children components as well.

The `React.memo()` function is a higher-order component (HOC) provided by React. It is used to memoize a component, which means that it caches the output of a component and returns it when the input props remain the same. The memoized component will only be re-rendered if its props have changed.

The `React.memo()` function is similar to the `shouldComponentUpdate()` lifecycle method, which is used to control when a component should be re-rendered. `React.memo()` is a simpler and more efficient way to achieve this, as it does not require you to implement the `shouldComponentUpdate()` method.

## **How does the React.memo() function work?**
When you use the `React.memo()` function to wrap a component, React will automatically compare the new props with the previous props. If the props are the same, React will use the cached output of the component and will not re-render it. If the props have changed, React will re-render the component and update the cached output.

_To show you what I mean.._

![Optimize React Component Performance with Memoization Using React.memo()](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/ir7ui9eqgnelxg86y2pf.png)

`MyComponent` component is memoized using the `React.memo()` function. This means that if the title and text props remain the same, the component will not be re-rendered.

To implement the `memo` function on a component at the export level, you can use an alternative approach:


![What is the React.memo() function?](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/u2a8dgfv73mbevas9u6b.png)

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## **What is memoization?**
Memoization caches the results of expensive functions to prevent repetitive computation and avoid redundant calls. This technique saves time and resources by storing the calculated results for future use.

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## **When to use the React.memo() function?**
The `React.memo()` function should be used when you have a component that receives props that do not change frequently. Memoizing such a component can improve performance by preventing unnecessary re-renders.

Notice this also, it is important to note that memoizing a component may not always improve performance. If a component receives props that change frequently, memoizing it may actually degrade performance, as React will spend more time checking for prop changes and updating the cached output.

It is also worth noting that memoizing a component is not a silver bullet for improving performance. There are other techniques, such as using the `useCallback()` hook, that can also be used to optimize React components. 

**In the upcoming days, I plan to create a well-crafted article that will delve into the functionality of the `useCallback` hook.**

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## **What is difference between React.memo function and useMomo() hook?**

`React.memo()` and `useMemo()` are both optimization techniques provided by React, but they serve different purposes. Let's see how..

The main purpose of `React.memo()` is to optimize the rendering of a component by caching its output based on its props. It's a higher-order component that you can use to wrap a component and enable this optimization.

On the otherside, the `useMemo()` hook is used to optimize the performance of expensive computations within a component. It allows you to memoize the result of a function call and use the cached result in subsequent renders, as long as the dependencies of the function have not changed. The `useMemo()` hook returns the cached result of the function call, which you can use in your component.

_To show you what I mean.._

![What is difference between React.memo function and useMomo() hook?](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/su0ygrws0lxtqra13dof.png)

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To wrap things up, the `React.memo()` function is a powerful tool that can help you optimize your React components. It allows you to memoize a component and cache its output, which can improve performance by preventing unnecessary re-renders. Even so, it should be used with care and only when it is appropriate for your specific use case..

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