Best Practices for Code Splitting in Web Development

Learn the importance of modular code organization, with examples of good and bad practices in React.js projects.

Effective code organization is key to maintaining a scalable, readable, and maintainable codebase. This document discusses good and bad practices in code splitting, particularly in the context of React.js development, and provides examples for a more modular code structure.

The Problem with Monolithic Code Structures ⚠️

Monolithic or single-file code structures can lead to several issues:

• Difficult Maintenance: Large files with mixed concerns are harder to understand and maintain.
• Poor Readability: Finding specific code segments becomes challenging as the file size grows. An example from personal experience is encountering files extending to 15,000 lines of code, which can be overwhelming and difficult to manage.
• Name Clashing: In extensive single files, reusing names for functions or components across different contexts can lead to conflicts and confusion, making debugging difficult.

Bad Practice Example 📛

Avoid placing all components, utilities, and types in one large file. For instance, defining multiple modals, utilities, and type declarations in a single file leads to clutter and confusion.

Example Large files

// Bad Practice: Everything in one file
import React from 'react';
// Imports for components, utilities, types all mixed together...

const MyComponent = () => { /* ... */ };
const AnotherComponent = () => { /* ... */ };
// Multiple components and utility functions defined here...

// thousands of lines of code... 🚂

export default MyComponent;

Good Practices in Code Splitting 🚀

Modular Component Structure

Organize components into separate files and directories. This improves readability and maintenance.

// Good Practice: Modular structure with sub-components
import React from 'react';
import SuccessModal from './SuccessModal';
// ...other imports

const Modal = ({ variant, ...props }) => {
  // Component logic
  return <div>{/* Render selected modal based on variant */}</div>;
};

export default Modal;

Example: Modal Component Structure

.
└── Modal/
    ├── index.jsx
    ├── SuccessModal.jsx
    ├── WarningModal.jsx
    ├── DangerModal.jsx
    ├── LoginModal.jsx

Modal Component Code example 🤓

Example: Modal Component code 👀

index.jsx

import React from 'react';

// ** import sub components
import SuccessModal from './SuccessModal';
import WarningModal from './WarningModal';
import DangerModal from './DangerModal';
import LoginModal from './LoginModal';

/**
 * @typedef {'success' | 'warning' | 'danger' | 'login'} ModalVariant
 * @typedef {'opaque' | 'blur' | 'transparent'} BackdropVariant
 * @typedef {'auto' | 'top' | 'center' | 'bottom' | 'bottom-center' | 'top-center'} placement
 */

/**
 * Modal component.
 *
 * @param {Object} props - The component props.
 * @param {ModalVariant} props.variant - The variant of the header to render.
 * @param {string} props.title
 * @param {string} props.description
 * @param {string} props.yesText
 * @param {string}props.noText
 * @param {Function} props.btnFunction - The function to call when button is clicked.
 * @param {Function} props.yesFunction - The function to call when 'yes' is clicked.
 * @param {Function} props.noFunction - The function to call when 'no' is clicked.
 * @param {BackdropVariant} props.backdropVariant - The variant of the backdrop to render.
 * @param {boolean} props.hideCloseButton - A boolean indicating whether a close button is present.
 * @param {boolean} props.outsideClickClose - The boolean indicating whether the modal should close when clicking outside the modal
 * @param {placement} props.placement - The placement of the modal
 * @returns {JSX.Element|null} The rendered header component.
 *
 */
const Modal = ({ variant, ...props }) => {
  const variantComponents = {
    success: SuccessModal,
    warning: WarningModal,
    danger: DangerModal,
    login: LoginModal
  };

  const SelectedModal = variantComponents[variant] || null;

  return <div>{SelectedModal && <SelectedModal {...props} />}</div>;
};

export default Modal;

Separate Utilities and Helpers

Place utility functions and helpers in separate files or directories.

Example: Utility Function

// utils/formatDate.js
export const formatDate = (date) => {
  // Format date logic
};

Define Types and Interfaces Separately

For TypeScript or PropTypes in React, define types or interfaces in dedicated files.

Example: Type Definitions

// types/modalTypes.ts
export type ModalVariant = 'success' | 'warning' | 'danger' | 'login';

Form Validation in Separate Files

Keep form validations separate, especially when using libraries like Formik or React Hook Form.

Example: Form Validation Logic

// validation/loginValidation.js
import * as Yup from 'yup';

export const loginValidationSchema = Yup.object().shape({
  // Validation schema
});

Additional Examples

• Component Styles: Define styles in separate CSS or SCSS files, or use CSS-in-JS styled components.
• API Calls: Separate API call functions into a dedicated service or API layer.
• Contexts and Hooks: Define React contexts and custom hooks in their own files. Conclusion Adopting a modular code structure by splitting your code into logical and coherent units not only enhances readability and maintainability but also prevents conflicts and encourages code reuse. This approach is essential in collaborative environments and large-scale applications.