Since its inception, React has completely transformed the way front-end developers build web-applications. With the help of virtual DOM, React can make UI updates more efficient than ever.

This often results in making your web applications snappier. However, there’s one thing that developers often complain about React. It’s the fact that why do medium-sized React web applications perform so poorly and slowly?

The answer to this question lies in the optimization techniques for React. If you can measure and optimize how your app’s components render, you can achieve significant improvements in the overall speed of the React apps. In this article, we’ll provide you with some best optimization techniques for React. So, without further ado, let’s begin.

Usage of Pure components

A React component is said to be pure if it gives out the same output for the same props and state. For such class components, React comes with Authorization base class. The class components which extend React.PureComponent class are considered as pure components.

Pure components are the same as that of the normal components except the fact they take care of shouldComponentUpdate. It also does shallow comparisons on prop and state data.

The component is not re-rendered if the previous props and state data is the same as that of the next state or props.

React.memo for component memorization

React.memo is similar to a PureComponent except PureComponent comes from class implementation for component. On the other hand, “memo” is utilized for creating functional component. Also, React.memo is a higher-order component.

Just like in the pure components, if the input props are the same, then the component rendering will be skipped thus increasing the speed and the efficiency of the component.

This is known for boosting the application performance by memorizing output from the last execution for a few input props.

It’s also possible to pass the custom comparison logic for this component. The custom logic allows the user to look for deep comparison of objects. The component is re-rendered if the comparison function returns false, otherwise, no re-rendering of the component takes place.

The shouldComponentUpdate Life Cycle Event

The shouldcomponentupdate life cycle event is triggered before the re-rendering of the component.

This event can be effectively utilized to decide when the component should be re-rendered.

This function returns a Boolean value whenever a setState is called or there is a change in the component props. The component tends to re-render in both cases.

This function also takes the nextProps and nextState as the input and then compares it with the current state and props to decide whether there is a requirement for re-rendering or not.

Binding vs. Arrow Functions in Constructors

The usage of arrow functions is considered as standard practice when you work with the classes. The usage of arrow functions helps in preserving the context of the execution.

Refrain from using Inline style attribute

The browser usually spends a huge amount of time in scripting and rendering with the inline style.

The scripting consumes a lot of time as it has to map all the style rules that are passed to the actual CSS properties. This results in increased rendering time for the component.

Avoid extra tags by using React fragments

A number of extra tags can be reduced by using fragments that are only required for having a common parent in the React component.

In a case when a user is creating a new component, then all the components mist only have a single parent tag. Two tags can’t dwell at the parent level. That’s why we must have a common tag at the top.

To fulfill this requirement, we generally add an extra tag at the top of the component.