What Are Top-Level Modules in JavaScript?

In JavaScript, "top-level modules" refer to modules that are directly executed at the top level of a JavaScript program or module. They are typically the entry point of an application or a module, functioning as standalone components that are not imported as dependencies within other modules.

For example, consider the following "main.js" entry point module:

// main.js
import colors from './modules/getColors.js';
import { Canvas } from './modules/canvas.js';

// ...

This is a very basic example, where the import statements will import the necessary modules (i.e. getColors.js and canvas.js) into the main module, allowing it to access and use the exported features from them.

You can load and execute the main.js module directly in the HTML file, for example, like so:

<script type="module" src="main.js"></script>

As an alternative, you may also inline your entry point inside the <script> tag, for example, in the following way:

<script type="module">
import colors from './modules/getColors.js';
import { Canvas } from './modules/canvas.js';

// ...
</script>

In either case, the top-level module is not imported as a dependency elsewhere. Instead, it is directly used and executed in the HTML file, serving as the entry point.

By using top-level modules, you can organize and structure your code in a modular and reusable manner, allowing for better code organization and separation of concerns.


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