1. Prop Drilling

Prop drilling occurs when properties are passed down through several layers of nested components. This practice can lead to performance issues and make the code harder to read. Instead, consider using React's Context API to share data more effectively. Here's a brief illustration:

// Parent component

function ParentComponent() {

const data = 'Some data';

return (

<ChildComponent data={data} />

);

}

// Child component

function ChildComponent({ data }) {

return (

<GrandchildComponent data={data} />

);

}

// Grandchild component

function GrandchildComponent({ data }) {

return <div>{data}</div>;

}

2. Excessive Imports

Over-importing libraries can bloat your application and slow down loading times. Always ensure you're importing only what you need. For instance, rather than importing an entire library, opt for specific functions:

// Poor practice - importing everything

import _ from 'lodash';

// Better practice - importing only necessary functions

import { someFunction } from 'lodash';

3. Mixing Business and UI Logic

Separating business logic from UI components enhances code clarity and maintainability. Extract business logic into separate service files or modules. Consider the following:

// Poor practice - business logic within components

function UserProfile() {

const user = getUserData(); // Fetch user data

return (

<div>

{user.name}

{user.email}

</div>

);

}

// Better practice - separation of concerns

function UserProfile() {

const user = useUserData(); // Fetch user data from a dedicated service

return (

<div>

{user.name}

{user.email}

</div>

);

}

4. Redundant Computations

Components in React may be re-rendered multiple times, leading to unnecessary computations. To avoid this, utilize useMemo and useCallback to memoize operations:

function List({ items }) {

// Without useMemo - filtering occurs on every render

const filteredItems = items.filter(item => item.active);

// With useMemo - filtering only recalculates if items change

const filteredItems = useMemo(() => items.filter(item => item.active), [items]);

}

5. Misusing the useEffect Hook

The useEffect hook is essential for managing side effects. Improper usage can lead to multiple event listeners being created. Always remember to return a cleanup function and use an empty dependency array to run the effect only once:

// Poor practice - event listener created on every render

useEffect(() => {

window.addEventListener('resize', handleResize);

return () => window.removeEventListener('resize', handleResize);

});

// Better practice - listener created only on mount

useEffect(() => {

window.addEventListener('resize', handleResize);

return () => window.removeEventListener('resize', handleResize);

}, []); // Empty dependency array

6. Boolean Operator Misuse

Incorrect use of Boolean operators can lead to unexpected results in your components. For instance:

// Poor practice - using && operator without proper checks

function ShoppingCart({ items }) {

return (

<div>

{items.length && Items in cart: ${items.length}}

</div>

);

}

// Better practice - convert condition to boolean

function ShoppingCart({ items }) {

return (

<div>

{Boolean(items.length) && Items in cart: ${items.length}}

</div>

);

}

7. Overusing Ternary Expressions

While ternary expressions are useful, excessive nesting can make code hard to read. Instead, consider using functions for clarity:

// Poor practice - multiple nested ternaries

function UserProfile({ user, isAdmin, isOwner }) {

return (

<div>

{isAdmin ? 'Admin' : isOwner ? 'Owner' : 'User'}

</div>

);

}

// Better practice - use a function for clarity

function UserProfile({ user, isAdmin, isOwner }) {

function getUserRole() {

if (isAdmin) return 'Admin';

if (isOwner) return 'Owner';

return 'User';

}

return (

<div>{getUserRole()}</div>

);

}

8. Not Defining Prop Types

Defining types and destructuring props is crucial for maintaining your code's stability. Utilize tools like PropTypes or TypeScript to enforce types:

// Poor practice - no prop types defined

function Person(props) {

return (

<div>

Name: {props.name}

Age: {props.age}

</div>

);

}

// Better practice - define prop types

import PropTypes from 'prop-types';

function Person({ name, age }) {

return (

<div>

Name: {name}

Age: {age}

</div>

);

}

Person.propTypes = {

name: PropTypes.string,

age: PropTypes.number,

};

9. Neglecting Code Splitting

For larger applications, implement code splitting to enhance initial load performance. This approach divides your code into smaller chunks, which can be loaded as needed:

import Loadable from 'react-loadable';

const AsyncComponent = Loadable({

loader: () => import('./AsyncComponent'),

loading: () => 'Loading...',

});

function App() {

return (

<div>

<AsyncComponent />

</div>

);

}