Uncaught SyntaxError: Cannot use import statement outside a module
—you’re not alone. This issue is surprisingly common, especially when integrating third-party libraries or misconfiguring modules. Let’s break down why it happens, what it means, and how to fix it effectively.
What Does the Error Mean?
The error message "Uncaught SyntaxError: Cannot use import statement outside a module" typically means that the JavaScript file trying to use an import statement is not being treated as a JavaScript module by the browser or build tool.
In the context of Angular, this usually indicates:
- A script is being loaded in a way that the browser does not recognize as a module.
- A library or dependency is being improperly referenced or used in the application.
- A misconfiguration in tsconfig.json, angular.json, or a build output.
???? Common Scenarios Where This Error Occurs
Let’s look at some real examples of when this error pops up:
1. Directly Importing an ES Module in index.html
<script src="some-es-module.js"></script>
If some-es-module.js contains import or export statements, it needs to be imported as a module:
✅ Correct usage:
<script type="module" src="some-es-module.js"></script>
Angular projects rarely need this unless you're doing custom scripting outside Angular.
2. Third-Party Library Not Transpiled
Sometimes, you import a library in Angular like this:
import SomeLibrary from 'some-esm-only-library';
If the library ships ES modules (.mjs or .js with ES6 imports) and your build system doesn’t transpile them to CommonJS or ES5 properly, you'll get this error in the browser.
3. Improper Configuration in tsconfig.json
Ensure your TypeScript configuration supports modules. Your tsconfig.json should include:
{
"compilerOptions": {
"module": "ESNext",
"target": "ES2015",
"moduleResolution": "node",
"typeRoots": ["node_modules/@types"],
...
}
}
Without proper module support, TypeScript may compile your code into incompatible JavaScript.
4. Wrong File Type (Using .js Instead of .ts)
If you're using a .js file in your Angular project with ES module syntax, and it's not being processed by the Angular CLI, the browser may treat it as a regular script, not a module.
How to Fix It
Here’s a step-by-step guide to fix the “Uncaught SyntaxError: Cannot use import statement outside a module” error in Angular:
✅ 1. Use type="module" in Scripts (if needed)
Only for scripts you directly include in HTML:
<script type="module" src="script.js"></script>
✅ 2. Avoid Direct <script> Tags for ESM Files
Don’t include third-party packages with <script> unless they're UMD builds or you use a bundler. Let Angular CLI handle imports via import statements in .ts files.
✅ 3. Use Angular CLI & Webpack for Imports
Stick to importing packages through TypeScript:
import { Something } from 'some-package';
Let Angular CLI and Webpack handle transpilation and bundling.
✅ 4. Check for .mjs Files
If you're importing .mjs files, you may need to configure Webpack to handle them:
{
test: /.mjs$/,
include: /node_modules/,
type: "javascript/auto"
}
This is more common in custom Angular setups or mono-repos.
Example: Fixing the Error in Practice
Suppose you're importing a library like this:
import { format } from 'date-fns';
And you're getting the error. Here's how to fix it:
- Ensure date-fns is installed via npm install date-fns.
- Update tsconfig.json:
"compilerOptions": {
"module": "ESNext",
"target": "ES2015"
}
- Don’t import it in index.html via a <script> tag. Use it in your component files.
Pro Tips to Avoid This Error
- Don’t mix <script> tags and import statements unless you know what you’re doing.
- Let Angular CLI handle all third-party libraries via npm.
- If you must use native modules outside Angular, load them using <script type="module">.
- Prefer .ts files and compile everything through Angular’s build pipeline.
Conclusion
The “Uncaught SyntaxError: Cannot use import statement outside a module” error in Angular typically signals that a file is being executed as a regular script instead of a module. This is mostly a configuration issue, and in Angular projects, it's best to let the CLI manage your module imports.
By following best practices and ensuring proper TypeScript and Angular configurations, you can avoid this error and ensure your application is built and run smoothly.
Read more on https://keploy.io/blog/community/cannot-use-import-statement-outside-a-module