Re-exporting in JavaScript Modules for better code management

Last update on July 19 2025 12:58:31 (UTC/GMT +8 hours)

Re-exporting:

Write a JavaScript module that re-exports functions from another module.

Solution-1:

JavaScript Code:

File: mathOperations.js

// --- file: mathOperations.js ---
// Export individual functions
export function add(a, b) {
  return a + b;
}

export function subtract(a, b) {
  return a - b;
}

File: advancedMath.js

// --- file: advancedMath.js ---
// Re-export functions from mathOperations.js
export { add, subtract } from './mathOperations.js';

// Add additional exports
export function multiply(a, b) {
  return a * b;
}

File: app.js

// --- file: app.js ---
// Import re-exported and additional functions
import { add, subtract, multiply } from './advancedMath.js';

// Use the imported functions
console.log(add(10, 5));         // Output: 15
console.log(subtract(10, 5));    // Output: 5
console.log(multiply(10, 5));    // Output: 50

Output:

15
5
50

Explanation:

'mathOperations.js' defines and exports 'add' and 'subtract' functions.
'advancedMath.js' re-exports 'add' and 'subtract' from 'mathOperations.js' and adds its own 'multiply' function.
'app.js' imports all functions seamlessly, benefiting from re-exporting to keep the module structure clean.

Solution-2:

JavaScript Code:

File: stringOperations.js

// --- file: stringOperations.js ---
// Export individual string utility functions
export function toUpperCase(str) {
  return str.toUpperCase();
}

export function toLowerCase(str) {
  return str.toLowerCase();
}

File: textUtils.js

// --- file: textUtils.js ---
// Re-export all exports from stringOperations.js
export * from './stringOperations.js';

// Add an additional export
export function capitalize(str) {
  return str.charAt(0).toUpperCase() + str.slice(1).toLowerCase();
}

File: main.js

// --- file: main.js ---
// Import re-exported and additional functions
import { toUpperCase, toLowerCase, capitalize } from './textUtils.js';

// Use the imported functions
console.log(toUpperCase('hello'));   // Output: HELLO
console.log(toLowerCase('WORLD'));   // Output: world
console.log(capitalize('javaScript')); // Output: Javascript

Output:

HELLO
world
Javascript

Explanation:

'stringOperations.js' defines and exports 'toUpperCase' and 'toLowerCase'.
'textUtils.js' re-exports all exports from 'stringOperations.js' using 'export *' syntax and adds a new 'capitalize' function.
'main.js' imports everything from 'textUtils.js', demonstrating how re-exporting simplifies and centralizes module management.

For more Practice: Solve these Related Problems:

Write a JavaScript module that re-exports specific functions from a utility module, filtering out non-essential exports.
Write a JavaScript module that aggregates and re-exports several functions from different modules into a single API.
Write a JavaScript module that re-exports named functions from another module with aliases and then use them in an application.
Write a JavaScript module that imports a module, selects a subset of its properties, and re-exports them for a streamlined interface.

Go to:

PREV : Combining Default and Named Exports.
NEXT : Import with Alias.

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