This error can happen in different cases depending on whether you're working with JavaScript on the server-side with Node.js , or client-side in the browser. There are several reasons behind "Cannot use import statement outside a module" error, and the solution depends on how you call the module or script tag.

Add type="module" inside the script tag

When working with ECMAScript modules and JavaScript module import statements in the browser, you'll need to explicitly tell the browser that a script is module. To do this, you have to add type="module" onto any ‹script› tags that point to a JavaScript module. Once you do this you can import that module without issues.

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

If you are working on Node.js or react applications and using import statements instead of require to load the modules, then ensure your package.json has a property "type": "module" as shown below.

{
  // ...
  "type": "module",
  // ...
}