Navigating Node.js Module Interactions: Unveiling Import-Export Patterns

Welcome back to our Node.js exploration! In this installment, we’re set to unravel some intriguing patterns you might encounter while importing and exporting modules in various projects. Each pattern is valid, and understanding them ensures you’re well-equipped for diverse coding scenarios.

Pattern One: Single Variable or Function Export

Let’s kick things off by creating a new file, math.js. Inside, we define a simple addition function:

// math.js
function add(a, b) {
  return a + b;
}

module.exports = add;

In our first pattern, we directly export a single variable or function. In index.js, we import and use it:

// index.js
const add = require('./math');

console.log(add(2, 3)); // Output: 5

Pattern Two: Direct Assignment to module.exports

In the second pattern, instead of having module.exports on a separate line, we assign the function directly:

// math.js updated
module.exports = function add(a, b) {
  return a + b;
};

The import in index.js remains the same, and the output should still be 5.

Pattern Three: Exporting Multiple Variables or Functions

Now, let’s explore exporting more than one variable or function. We modify math.js:

// math.js updated
function add(a, b) {
  return a + b;
}

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

module.exports = { add, subtract };

In index.js, we import and use both functions:

// index.js updated
const math = require('./math');

console.log(math.add(2, 3));      // Output: 5
console.log(math.subtract(2, 3)); // Output: -1

Pattern Four: Direct Assignment Within module.exports

An alternative way to attach functions to module.exports is by directly assigning them:

// math.js updated
module.exports.add = function(a, b) {
  return a + b;
};

module.exports.subtract = function(a, b) {
  return a - b;
};

This change does not affect the import or output in index.js.

Pattern Five: Leveraging exports Reference

In the fifth pattern, we revisit the function that wraps every module. Instead of module.exports, we use the shorthand exports:

// math.js updated
exports.add = function(a, b) {
  return a + b;
};

exports.subtract = function(a, b) {
  return a - b;
};

While this works and produces the same output, it’s generally advisable to stick with module.exports for consistency and clarity.

Intrigued to know why? Stay tuned for the next video, where we’ll delve into the nuances of module.exports versus exports.

I hope these patterns provide you with a comprehensive view of module interactions in Node.js.