Every React.js developer must know — How module system organization works in React?

Have you ever wondered why the export and import module syntax, which is commonly used in React.js for organizing and importing code, doesn’t work in native JavaScript? This inconsistency can lead to confusion, especially when developers attempt to use similar techniques in non-React projects.

The export and import module syntax is not natively supported in most web browsers. Native JavaScript (also known as Vanilla JavaScript) lacks built-in support for module loading and dependency management. This means that attempting to use export and import statements in a traditional JavaScript environment outside of frameworks like React.js will result in syntax errors.

Frameworks like React.js, along with modern JavaScript development tools like Webpack and Babel, provide solutions to this problem. React.js leverages these tools to transpile and bundle code written using export and import statements into a format that browsers can understand. Behind the scenes, Babel converts modern JavaScript syntax (ES6+) into a backwards-compatible version (ES5) that can run in older browsers. Additionally, Webpack bundles all the necessary modules and dependencies into a single or multiple files, ensuring that the application loads and runs smoothly in any browser environment.

So, while export and import statements may not work directly in native JavaScript, frameworks like React.js, combined with tools like Babel and Webpack, offer robust solutions for organizing, importing, and managing modules in modern web development.

Overview of the Module System in React

In React, the module system is a way to organize and manage your code. It allows you to split your code into smaller, reusable parts called modules. These modules can be functions, components, or even just variables that you want to use in different parts of your application.

Modularization, or breaking your code into smaller modules, is crucial in modern JavaScript development for a few reasons. Firstly, it helps keep your code organized and easier to understand. Instead of having one big file with all your code in it, you can split it up into smaller, more manageable pieces.

Example -

Let’s see an example of how a simple React component written using modern ES6+ syntax and JSX gets transpiled step by step:

Below is the React Component Written in ES6+ and JSX:

// ReactComponent.jsx
import React from 'react';

const ReactComponent = () => {
  return (
    <div className="container">
      <h1>Hello, World!</h1>
    </div>
  );
}

export default ReactComponent;

Here’s how it gets transpiled step by step:

Step 1: Transpile JSX to JavaScript:

The JSX syntax in the return statement needs to be transpiled into plain JavaScript function calls. Babel will convert it into React.createElement() calls.

// Transpiled JavaScript
import React from 'react';

const ReactComponent = () => {
  return React.createElement(
    'div',
    { className: 'container' },
    React.createElement('h1', null, 'Hello, World!')
  );
}

export default ReactComponent;

Step 2: Transpile ES6+ Syntax:

Next, Babel transpiles any ES6+ syntax into equivalent ES5 code. In this example, there isn’t much ES6+ syntax, but let’s say we had arrow functions. They would be converted to regular function expressions.

// Transpiled JavaScript (with ES6+ converted)
"use strict";

var _react = _interopRequireDefault(require('react'));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "default": obj }; }

var ReactComponent = function ReactComponent() {
  return _react["default"].createElement(
    'div',
    { className: 'container' },
    _react["default"].createElement('h1', null, 'Hello, World!')
  );
};

export default ReactComponent;

Step 3: Module Handling and Bundling:

Finally, bundlers like Webpack take the transpiled JavaScript code and bundle it along with other dependencies into a single or multiple files for deployment. The bundled code will typically have all the necessary modules included and optimized for production.

This bundled JavaScript code can be quite large and complex, so it’s often minified and optimized further to improve performance.

So, the final bundled code might look something like this:

// Bundled JavaScript (minified and bundled)
"use strict";var e=require("react");function t(){return e.createElement("div",{className:"container"},e.createElement("h1",null,"Hello, World!"))}export default t;

In this way, the original React code written in ES6+ and JSX is transformed step by step into a form that’s compatible with older browsers and suitable for deployment.

Conclusion

In wrapping up, we’ve explored how React handles exporting and importing modules, vital for organizing code and making it reusable. We’ve peeked behind the curtain to see how bundlers like Webpack manage these imports and exports, and how Babel ensures our modern React code works smoothly across different browsers.

By breaking down a React component from modern ES6+ and JSX to browser-friendly JavaScript, we’ve seen how the process unfolds, ensuring our code is efficient and compatible. Understanding these fundamentals empowers React developers to build robust and scalable applications with ease.