Does Es6 Module Importing Execute The Code Inside The Imported File

ES6 Module Importing is a powerful feature in modern JavaScript that allows developers to organize their code in a clean, modular way. When importing a module, it's natural to wonder: does importing an ES6 module execute the code inside the imported file?

The short answer is yes, importing an ES6 module does execute the code inside the imported file. However, it's important to understand how ES6 module loading works to grasp the full picture.

When you import a module using the `import` statement in JavaScript, the module is fetched, parsed, and evaluated. This process involves executing the code inside the imported file. This behavior differs from earlier module loading methods like CommonJS, where code inside a module was only executed when the module was required.

ES6 Modules provide a more efficient way of managing dependencies and ensure that code inside a module is only executed once, even if the module is imported multiple times in your application.

Let's look at an example to illustrate this concept:

// math.js
console.log("Executing code inside math.js");

export function sum(a, b) {
  return a + b;
}

// app.js
import { sum } from './math.js';

console.log(sum(2, 3));

In this example, when `app.js` imports the `sum` function from `math.js`, the code inside `math.js` is executed, and you'll see the log statement "Executing code inside math.js" in the console.

This behavior is beneficial because it ensures that the code inside the imported file runs exactly when needed, maintaining a clean and modular structure in your application.

However, it's important to note that the code inside an ES6 module is executed only once per execution context. This means that subsequent imports of the same module in different parts of your application won't cause the code inside the module to be re-executed. The exports from the module are shared across all importers.

If you have initialization logic or side effects inside your module that should only run once, ES6 Modules provide a reliable way to handle this scenario.

In conclusion, when you import an ES6 module, the code inside the imported file is indeed executed. Understanding how ES6 module loading works can help you leverage this feature effectively in your projects, ensuring clean, organized, and efficient code.

So go ahead, import those modules, and let your JavaScript code shine with the power of ES6 Modules!