JavaScript Modules with Tree Shaking Techniques

Tree Shaking:

Write a JavaScript program to create a module with multiple exports and import only the functions needed.

Tree shaking is a technique for eliminating unused code in JavaScript. In this exercise, we’ll create a module with multiple exports and demonstrate importing only the required functions.

Solution-1: Using Named Exports with Direct Imports

Code:

File: mathUtils.js

This file defines multiple mathematical utility functions.

// mathUtils.js
// Exporting multiple functions from mathUtils.js
export const add = (a, b) => a + b; // Adds two numbers
export const subtract = (a, b) => a - b; // Subtracts two numbers
export const multiply = (a, b) => a * b; // Multiplies two numbers
export const divide = (a, b) => a / b; // Divides two numbers

File: main.js

This file imports only the required functions.

// main.js  
// Importing only the required functions
import { add, multiply } from './mathUtils.js';

// Using the imported functions
console.log(add(4, 3)); // Logs 7
console.log(multiply(5, 6)); // Logs 30

Output:

7
30

Explanation:

• mathUtils.js defines and exports four mathematical utility functions using named exports.
• main.js imports only the add and multiply functions, leaving the unused exports (subtract and divide) untouched.
• This selective import ensures that only the required functions are included in the final bundle during tree shaking.

Solution-2: Combining Tree Shaking with Default Export

Code:

File: mathUtils.js

This file exports a single utility object containing multiple functions.

// mathUtils.js
// Exporting a utility object containing multiple functions
const mathUtils = {
  add: (a, b) => a + b, // Adds two numbers
  subtract: (a, b) => a - b, // Subtracts two numbers
  multiply: (a, b) => a * b, // Multiplies two numbers
  divide: (a, b) => a / b, // Divides two numbers
};
export default mathUtils;

File: main.js

This file destructures and uses only the required functions.

// main.js  
// Importing the default export and destructuring only the required functions
import mathUtils from './mathUtils.js';
const { add, divide } = mathUtils;

// Using the destructured functions
console.log(add(8, 2)); // Logs 10
console.log(divide(20, 4)); // Logs 5  

Output:

10
5

Explanation:

• mathUtils.js exports all functions within a single object using a default export.
• In main.js, the utility object is imported, and only the add and divide functions are destructured and used.
• This approach can still benefit from tree shaking if the build tool understands unused properties of the object.

For more Practice: Solve these Related Problems:

• Write a JavaScript module that exports multiple functions and import only the ones needed in another file to demonstrate tree shaking.
• Write a JavaScript program that uses ES6 import syntax to selectively import functions from a module and logs unused exports.
• Write a JavaScript module with several named exports and then create a build process that eliminates unused code.
• Write a JavaScript program that benchmarks the performance difference between importing all exports and only importing the necessary ones.

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