I've got an ApolloServer project that's giving me trouble, so I thought I might update it and ran into issues when using the latest Babel. My "index.js" is:
require('dotenv').config()
import {startServer} from './server'
startServer()
And when I run it I get the error
SyntaxError: Cannot use import statement outside a module
First I tried doing things to convince TPTB* that this was a module (with no success). So I changed the "import" to a "require" and this worked.
But now I have about two dozen "imports" in other files giving me the same error.
*I'm sure the root of my problem is that I'm not even sure what's complaining about the issue. I sort of assumed it was Babel 7 (since I'm coming from Babel 6 and I had to change the presets) but I'm not 100% sure.
Most of what I've found for solutions don't seem to apply to straight Node. Like this one here:
ES6 module Import giving "Uncaught SyntaxError: Unexpected identifier"
Says it was resolved by adding "type=module" but this would typically go in the HTML, of which I have none. I've also tried using my project's old presets:
"presets": ["es2015", "stage-2"],
"plugins": []
But that gets me another error: "Error: Plugin/Preset files are not allowed to export objects, only functions."
Here are the dependencies I started with:
"dependencies": {
"#babel/polyfill": "^7.6.0",
"apollo-link-error": "^1.1.12",
"apollo-link-http": "^1.5.16",
"apollo-server": "^2.9.6",
"babel-preset-es2015": "^6.24.1",
Verify that you have the latest version of Node.js installed (or, at least 13.2.0+). Then do one of the following, as described in the documentation:
Option 1
In the nearest parent package.json file, add the top-level "type" field with a value of "module". This will ensure that all .js and .mjs files are interpreted as ES modules. You can interpret individual files as CommonJS by using the .cjs extension.
// package.json
{
"type": "module"
}
Option 2
Explicitly name files with the .mjs extension. All other files, such as .js will be interpreted as CommonJS, which is the default if type is not defined in package.json.
If anyone is running into this issue with TypeScript, the key to solving it for me was changing
"target": "esnext",
"module": "esnext",
to
"target": "esnext",
"module": "commonjs",
In my tsconfig.json. I was under the impression "esnext" was the "best", but that was just a mistake.
For those who were as confused as I was when reading the answers, in your package.json file, add
"type": "module"
in the upper level as show below:
{
"name": "my-app",
"version": "0.0.0",
"type": "module",
"scripts": { ...
},
...
}
According to the official documentation:
import statements are permitted only in ES modules. For similar functionality in CommonJS, see import().
To make Node.js treat your file as an ES module, you need to (Enabling):
add "type": "module" to package.json
add "--experimental-modules" flag to the Node.js call
I ran into the same issue and it's even worse: I needed both "import" and "require"
Some newer ES6 modules works only with import.
Some CommonJS works with require.
Here is what worked for me:
Turn your js file into .mjs as suggested in other answers
"require" is not defined with the ES6 module, so you can define it this way:
import { createRequire } from 'module'
const require = createRequire(import.meta.url);
Now 'require' can be used in the usual way.
Use import for ES6 modules and require for CommonJS.
Some useful links: Node.js's own documentation. difference between import and require. Mozilla has some nice documentation about import
I had the same issue and the following has fixed it (using Node.js 12.13.1):
Change .js files extension to .mjs
Add --experimental-modules flag upon running your app.
Optional: add "type": "module" in your package.json
More information: https://nodejs.org/api/esm.html
First we'll install #babel/cli, #babel/core and #babel/preset-env:
npm install --save-dev #babel/cli #babel/core #babel/preset-env
Then we'll create a .babelrc file for configuring Babel:
touch .babelrc
This will host any options we might want to configure Babel with:
{
"presets": ["#babel/preset-env"]
}
With recent changes to Babel, you will need to transpile your ES6 before Node.js can run it.
So, we'll add our first script, build, in file package.json.
"scripts": {
"build": "babel index.js -d dist"
}
Then we'll add our start script in file package.json.
"scripts": {
"build": "babel index.js -d dist", // replace index.js with your filename
"start": "npm run build && node dist/index.js"
}
Now let's start our server.
npm start
I Tried with all the methods, but nothing worked.
I got one reference from GitHub.
To use TypeScript imports with Node.js, I installed the below packages.
1. npm i typescript --save-dev
2. npm i ts-node --save-dev
Won't require type: module in package.json
For example,
{
"name": "my-app",
"version": "0.0.1",
"description": "",
"scripts": {
},
"dependencies": {
"knex": "^0.16.3",
"pg": "^7.9.0",
"ts-node": "^8.1.0",
"typescript": "^3.3.4000"
}
}
Step 1
yarn add esm
or
npm i esm --save
Step 2
package.json
"scripts": {
"start": "node -r esm src/index.js",
}
Step 3
nodemon --exec npm start
Node v14.16.0
For those who've tried .mjs and got:
Aviator#AW:/mnt/c/Users/Adrian/Desktop/Programming/nodejs_ex$ node just_js.mjs
file:///mnt/c/Users/Adrian/Desktop/Programming/nodejs_ex/just_js.mjs:3
import fetch from "node-fetch";
^^^^^
SyntaxError: Unexpected identifier
and who've tried import fetch from "node-fetch";
and who've tried const fetch = require('node-fetch');
Aviator#AW:/mnt/c/Users/Adrian/Desktop/Programming/nodejs_ex$ node just_js.js
(node:4899) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
/mnt/c/Users/Adrian/Desktop/Programming/nodejs_ex/just_js.js:3
import fetch from "node-fetch";
^^^^^^
SyntaxError: Cannot use import statement outside a module
and who've tried "type": "module" to package.json, yet continue seeing the error,
{
"name": "test",
"version": "1.0.0",
"description": "to get fetch working",
"main": "just_js.js",
"type": "module",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "",
"license": "MIT"
}
I was able to switch to axios without a problem.
import axios from 'axios'; <-- put at top of file.
Example:
axios.get('https://www.w3schools.com/xml/note.xml').then(resp => {
console.log(resp.data);
});
I found the 2020 update to the answer in this link helpful to answering this question as well as telling you WHY it does this:
Using Node.js require vs. ES6 import/export
Here's an excerpt:
"Update 2020
Since Node v12, support for ES modules is enabled by default, but it's still experimental at the time of writing this. Files including node modules must either end in .mjs or the nearest package.json file must contain "type": "module". The Node documentation has a ton more information, also about interop between CommonJS and ES modules."
I'm new to Node.js, and I got the same issue for the AWS Lambda function (using Node.js) while fixing it.
I found some of the differences between CommonJS and ES6 JavaScript:
ES6:
Add "type":"module" in the package.json file
Use "import" to use from lib.
Example: import jwt_decode from jwt-decode
Lambda handler method code should be define like this
"exports.handler = async (event) => { }"
CommonJS:
Don't add "type":"module" in the package.json file
Use "require" to use from lib.
Example: const jwt_decode = require("jwt-decode");
The lambda handler method code should be defines like this:
"export const handler = async (event) => { }"
In my case. I think the problem is in the standard node executable. node target.ts
I replaced it with nodemon and surprisingly it worked!
The way using the standard executable (runner):
node target.ts
The way using the nodemon executable (runner):
nodemon target.ts
Do not forget to install nodemon with npm install nodemon ;P
Note: this works amazing for development. But, for runtime, you may execute node with the compiled js file!
To use import, do one of the following.
Rename the .js file to .mjs
In package.json file, add {type:module}
If you are using ES6 JavaScript imports:
install cross-env
in package.json change "test": "jest" to "test": "cross-env NODE_OPTIONS=--experimental-vm-modules jest"
more in package.json, add these:
...,
"jest": {
"transform": {}
},
"type": "module"
Explanation:
cross-env allows to change environment variables without changing the npm command. Next, in file package.json you change your npm command to enable experimental ES6 support for Jest, and configure Jest to do it.
This error also comes when you run the command
node filename.ts
and not
node filename.js
Simply put, with the node command we will have to run the JavaScript file (filename.js) and not the TypeScript file unless we are using a package like ts-node.
If you want to use BABEL, I have a simple solution for that!
Remember this is for nodejs example: like an expressJS server!
If you are going to use react or another framework, look in the babel documentation!
First, install (do not install unnecessary things that will only trash your project!)
npm install --save-dev #babel/core #babel/node
Just 2 WAO
then config your babel file in your repo!
file name:
babel.config.json
{
"presets": ["#babel/preset-env"]
}
if you don't want to use the babel file, use:
Run in your console, and script.js is your entry point!
npx babel-node --presets #babel/preset-env -- script.js
the full information is here; https://babeljs.io/docs/en/babel-node
I had this error in my NX workspace after upgrading manually. The following change in each jest.config.js fixed it:
transform: {
'^.+\\.(ts|js|html)$': 'jest-preset-angular',
},
to
transform: {
'^.+\\.(ts|mjs|js|html)$': 'jest-preset-angular',
},
I had this issue when I was running migration
Its es5 vs es6 issue
Here is how I solved it
I run
npm install #babel/register
and add
require("#babel/register")
at the top of my .sequelizerc file my
and go ahead to run my sequelize migrate.
This is applicable to other things apart from sequelize
babel does the transpiling
Just add --presets '#babel/preset-env'.
For example,
babel-node --trace-deprecation --presets '#babel/preset-env' ./yourscript.js
Or
in babel.config.js
module.exports = {
presets: ['#babel/preset-env'],
};
To make your import work and avoid other issues, like modules not working in Node.js, just note that:
With ES6 modules you can not yet import directories. Your import should look like this:
import fs from './../node_modules/file-system/file-system.js'
For people coming to this thread due to this error in Netlify functions even after adding "type": "module" in package.json file, update your netlify.toml to use 'esbuild'. Since esbuild supports ES6, it would work.
[functions]
node_bundler = "esbuild"
Reference:
https://docs.netlify.com/functions/build-with-javascript/#automated-dependency-bundling
The documentation is confusing. I use Node.js to perform some local task in my computer.
Let's suppose my old script was test.js. Within it, if I want to use
import something from "./mylocalECMAmodule";
it will throw an error like this:
(node:16012) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
SyntaxError: Cannot use import statement outside a module
...
This is not a module error, but a Node.js error. Forbid loading anything outside a 'module'.
To fix this, just rename your old script test.js into test.mjs.
That's all.
My solution was to include babel-node path while running nodemon as follows:
nodemon node_modules/.bin/babel-node index.js
You can add in your package.json script as:
debug: nodemon node_modules/.bin/babel-node index.js
NOTE: My entry file is index.js. Replace it with your entry file (many have app.js/server.js).
I had the same problem when I started to use Babel... But later, I
had a solution... I haven't had the problem any more so far...
Currently, Node.js v12.14.1, "#babel/node": "^7.8.4", I use babel-node and nodemon to execute (Node.js is fine as well..)
package.json: "start": "nodemon --exec babel-node server.js "debug": "babel-node debug server.js"!! Note: server.js is my entry
file, and you can use yours.
launch.json. When you debug, you also need to configure your launch.json file "runtimeExecutable":
"${workspaceRoot}/node_modules/.bin/babel-node"!! Note: plus
runtimeExecutable into the configuration.
Of course, with babel-node, you also normally need and edit another file, such as the babel.config.js/.babelrc file
In case you're running nodemon for the Node.js version 12, use this command.
server.js is the "main" inside package.json file, replace it with the relevant file inside your package.json file:
nodemon --experimental-modules server.js
I recently had the issue. The fix which worked for me was to add this to file babel.config.json in the plugins section:
["#babel/plugin-transform-modules-commonjs", {
"allowTopLevelThis": true,
"loose": true,
"lazy": true
}],
I had some imported module with // and the error "cannot use import outside a module".
If you are using node, you should refer to this document. Just setup babel in your node app it will work and It worked for me.
npm install --save-dev #babel/cli #babel/core #babel/preset-env
When I used sequelize migrations with npx sequelize db:migrate, I got this error, so my solution for this was adding the line require('#babel/register'); into the .sequelizerc file as the following image shows:
Be aware you must install Babel and Babel register.
Wrong MIME-Type for JavaScript Module Files
The common source of the problem is the MIME-type for "Module" type JavaScript files is not recognized as a "module" type by the server, the client, or the ECMAScript engine that process or deliver these files.
The problem is the developers of Module JavaScript files incorrectly associated Modules with a new ".mjs" (.js) extension, but then assigned it a MIME-type server type of "text/javascript". This means both .js and .mjs types are the same. In fact the new type for .js JavaScript files has also changed to "application/javascript", further confusing the issue. So Module JavaScript files are not being recognized by any of these systems, regardless of Node.js or Babel file processing systems in development.
The main problem is this new "module" subtype of JavaScript is yet known to most servers or clients (modern HTML5 browsers). In other words, they have no way to know what a Module file type truly is apart from a JavaScript type!
So, you get the response you posted, where the JavaScript engine is saying it needs to know if the file is a Module type of JavaScript file.
The only solution, for server or client, is to change your server or browser to deliver a new Mime-type that trigger ES6 support of Module files, which have an .mjs extension. Right now, the only way to do that is to either create a HTTP content-type on the server of "module" for any file with a .mjs extension and change your file extension on module JavaScript files to ".mjs", or have an HTML script tag with type="module" added to any external <script> element you use that downloads your external .js JavaScript module file.
Once you fool the browser or JavaScript engines into accepting the new Module file type, they will start doing their scripting circus tricks in the JS engines or Node.js systems you use.
Firstly, I am very to the world or Node.js etc so apologies if this is an obvious problem.
I am creating a custom packages with a few components:
One component for example is this?
class MailProcess {
constructor(name, code) {
this.name = name;
this.code = code;
}
}
module.exports = {MailProcess: MailProcess};
and in my index file:
export {MailProcess} from "./mail/MailProcess";
// export more components like above
and my json file:
{
"name": "packagename",
"version": "1.0.3",
"description": "Private package",
"main": "index.js",
"publishConfig": {
"registry": "https://npm.pkg.github.com/...."
},
"scripts": {
"start": "node index.js"
},
"keywords": [],
"author": "",
"license": "ISC",
"dependencies": {
"aws-sdk": "^2.1172.0",
"mysql": "^2.18.1"
}
}
and in my Main code I (after installing the above package) I implement like this:
let {MailProcess} = require('#myusername/mypackagename');
but the error get thrown of
SyntaxError: Unexpected token 'export' relating to the index file.
I am wondering what I might be doing wrong. Essentially my pack contains a few different classes and I try to export them in index so the code using this package has access
Thanks for any help
Ok so I had this same issue, albeit with a different setup and I stumbled upon this question. At this point it may not be needed anymore, but I wanted to share what solved the problem in my case, in case it may help somebody else down the line.
My setup was basically a NodeJs (v16) project acting as a server, a frontend (not relevant to the problem) and the shared Types package.
My issue was that while everything worked fine when using npm link, it would not when publishing the Types package and installing it. Needless to say that the error was the same one:
export * from "./blocks";
^^^^^^
SyntaxError: Unexpected token 'export'
More specifically, in the top level index.ts of the Types package, which was "exporting everything out".
To give an idea, this was the relevant part of my package.json for my Types package:
"name": "vnotes-types",
"version": "1.1.3",
"description": "types for the VNotes application",
"main": "./src/index.ts",
"scripts": {
"compile": "tsc"
},
Moreover, on tsc I was compiling everything to a ./lib folder.
And the solution, basically, was:
Changing "main": "./src/index.ts" to "main": "./lib/index.js",. Here the problem was that I would employ the non-compiled index.ts (/src/index.ts) and import everything from there.
Adding "types": "./lib/index.d.ts". Basically points out to the type declarations.
I think this one isn't 100% necessary, but it reduces the size and clutter of the package: "files": ["./lib"] will only bundle the /lib folder, so your /src folder won't be included in the installation.
Hope this one helps people avoid wasting a stupid amount of time like I did to solve this issue.
I'm currently having a weird issue:
Uncaught (in promise) ReferenceError: Cannot access 'Agile' before initialization,
which is probably caused by webpack trying to correctly transform the ESM part of my library into CommonJs. Unfortunately, it doesn't do a good job and I end up with the error mentioned above.
My library supports both: CommonJs and ESM. So I'm wondering why webpack uses the ESM part and transforms it into CommonJs, instead of directly using the CommonJs part of my library?!
Why am I so sure that it has something to do with the ESM to CommonJs transformation?
Well, I once forced webpack to use the CommonJs part of my library by removing the ESM support. By doing so, I simply deleted the path to the ESM module in the package.json of my library.
"module": "dist/esm/index.js"
After unsupporting ESM, webpack was forced to use the CommonJs part
and it works as expected, since webpack doesn't have to transform anything anymore. (see image)
ESM transformed to CommonJS [not working]
Untransformed CommonJS [working]
Since my library should support both: ESM and CommonJS,
simply unsupporting ESM is no solution.
Here is the package.json of my library:
{
"name": "#agile-ts/core",
"version": "0.2.0+17b078aa",
"author": "BennoDev",
"license": "MIT",
"homepage": "https://agile-ts.org/",
"description": "Spacy, Simple, Scalable State Management Framework",
"keywords": [
// ..
],
"main": "dist/index.js", // <!-- CommonJs
"module": "dist/esm/index.js", // <!-- ESM
"types": "dist/index.d.ts",
"scripts": {
// ..
},
"dependencies": {
"#agile-ts/utils": "^0.0.8"
},
"peerDependencies": {
"#agile-ts/logger": "^0.0.8"
},
"peerDependenciesMeta": {
"#agile-ts/logger": {
"optional": true
}
},
"publishConfig": {
"access": "public"
},
"repository": {
"type": "git",
"url": "https://github.com/agile-ts/agile.git"
},
"bugs": {
"url": "https://github.com/agile-ts/agile/issues"
},
"files": [
"dist",
"LICENSE",
"README.md",
"CHANGELOG.md"
],
"sideEffects": false
}
Maybe I've misconfigured something in the package.json
and thus webpack uses ESM although it requires CommonJs?
Node Version: v16.3.0
Github Repo: https://github.com/agile-ts/agile/tree/master/packages/core
Ok, I fixed this issue by resolving all circular dependencies ^^
See: https://github.com/agile-ts/agile/issues/193
I'm currently trying to load a Leaflet map in a personal project.
but my code does not execute because of an import problem.
i installed leaflet type definitions with the following command
npm install --save #types/leaflet
it has one dependency so ive installed geojson too
npm install --save #types/geojson
this is part of my tsconfig.json file
{
"compilerOptions": {
"typeRoots": ["node_modules/#types"],
"rootDir": ".",
"outDir": "build",
"target": "es2018",
"lib": [
"es2018",
"dom"
],
"types": [
"leaflet",
"geojson"
]
},
"include": [
"src/**/*.ts"
],
"exclude": [
"node_modules"
]
}
i'm following the basic example in the documentation of leaflet, but instead of writing inline code i made a class.
this is a part of the index where i load all my js files, the map div is inside the body (not shown here).
<link rel="stylesheet" type="text/css" href="ts\node_modules\leaflet\dist\leaflet.css">
<script src="ts\node_modules\leaflet\dist\leaflet.js"></script>
<script src="./ts/build/src/mapsmanager.js" type="module"></script>
<script type="module">
// Import classes
import { MapsManager } from './ts/build/src/mapsmanager.js';
initialize();
function initialize()
{
/* ADD MAP SCRIPT */
let mapsman = new MapsManager();
}
</script>
this is my mapsmanager.ts file where i get the error from
import * as Leaf from 'leaflet';
export class MapsManager
{
/*DO STUFF*/
}
this line
import * as Leaf from 'leaflet';
gives me the following runtime error:
TypeError: Error resolving module specifier: leaflet
i've also tried to load leaflet as a module
<script src="ts\node_modules\leaflet\dist\leaflet.js" type="module"></script>
but it didn't work, it gave me another runtime error:
TypeError: t is undefined (inside leaflet.js)
IMPORTANT
without using classes and by using inline JS inside the index the map works fine. it has probably something to do with the project configuration/declarations/definitions/modules stuff or maybe even leaflet.
this is part of my package.json
"files": [
"build",
"src"
],
"devDependencies": {
"gts": "^2.0.0",
"typescript": "~3.8.0",
"#types/node": "^10.0.3"
},
"dependencies": {
"#types/geojson": "^7946.0.7",
"#types/leaflet": "^1.5.12",
"leaflet": "^1.6.0"
}
I've also tried to add a index.d.ts file where i put a declaration of the leaflet module because before leaflet i tried to use Google Maps JS API which uses this method but it didn't work.
I hope my description of the problem have been exhaustive
The issue is very probably caused by the 2 different uses of import in your architecture:
As TypeScript import (for both the library and automatically resolved corresponding types)
As in browser script module import
For TypeScript transpilation step, the transpiler knows that an absolute path ("leaflet") can be in your project "node_modules" folder.
But that is not the case for in browser module import: here you need to specify the exact (may be relative) path to your file (or at least the location of the module package.json file), similarly to what you would have specified in the src attribute of a <script> tag.
In this case, you have to modify the "import leaflet" path so that the final JS file has correct path.
Since that would probably break the step 1 TypeScript, you then need to update your tsconfig to tell TypeScript how to resolve that path. See e.g. TypeScript Import Path Alias
Note: usually this is not an issue because very few people actually use in browser module import, but instead use a build engine (which can encompass the TypeScript transpilation step) which bundles all JS in a single file (e.g. webpack or Rollup), therefore the resolution is all made at build stage, and you can configure all the resolvers so they look into your "node_modules" folder (default behaviour obviously, so usually no special configuration is needed).