The common JavaScript error "Cannot use import statement outside a module" indicates issues in importing modules and occurs in non-ECMAScript Module (ESM). Here’s a quick solution for both Browser and Node.js (sometimes referred to as "server-side JavaScript") environments.

Browser

Ensure your JavaScript code runs in ESM by using the module type script tag:

<!-- Before -->
<script src="your-file.js"></script>

<!-- After -->
<script type="module" src="your-file.js"></script>

If you have concerns about whether your users’ browsers support the type="module" directive, check out the "JavaScript modules via script tag" page on Can I use.

Node.js / server-side

There are two key ways to resolve this error.

Updating the file extension

Try changing the ‘.js’ extension to ‘.mjs’: Node.js treats ‘.mjs’ as ES modules.

$ mv server.js server.mjs

If that doesn’t work, you can modify the project’s package.json. Include "type": "module" to your package.json to interpret ‘.js’ files as ES modules.

{
  "type": "module",
}

If you don’t have a package.json for your project, run npm init -y to create one first.