Why Am I Getting a 'SyntaxError: Cannot use import statement outside a module' in Node.js?

"SyntaxError: Cannot use import statement outside a module" Explained and Resolved

In Node.js projects, the error "SyntaxError: Cannot use import statement outside a module" indicates that an import statement is being used in a file that is not recognized as an ES module. This issue commonly arises when upgrading to newer versions of Babel or Node.js.

Understanding the Issue

In Babel 7, the default behavior is to interpret files with the .js extension as CommonJS modules. ES modules, on the other hand, require a "type" field set to "module" in the nearest package.json file or explicit naming with the .mjs extension.

Resolving the Error

There are two options to resolve this error:

Option 1: Set "type" to "module" in package.json

Add the following "type" field to your package.json file:

// package.json
{
  "type": "module"
}

This will interpret all .js and .mjs files as ES modules, while individual files can still be interpreted as CommonJS by using the .cjs extension.

Option 2: Explicitly use the .mjs extension

Explicitly name files that should be treated as ES modules with the .mjs extension. All other files with the .js extension will be interpreted as CommonJS by default.

Additional Considerations

• Ensure you have the latest version of Node.js installed (13.2.0 is recommended).
• If you were previously using Babel 6, it's necessary to update the presets to avoid further errors.
• It's important to consistently use ES modules or CommonJS modules throughout a project to maintain compatibility.

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