I am trying since several days to build a node module which will be used by a react application.
Today my module is packaged as a big javascript file packaged with webpack.
Some part of this node module is optional and is only needed if we want to use certain features (activated through config). In order to avoid loading unecessary part of the code, I have tried first to use chunking and dynamic import as explained by webpack but this has not worked: chunks are created and packaged in the dist/ folder but i never succeed to run the dynamic import in the node module when called from the react app. The application complains that the chunk cannot be loaded from the app. This make sense for me as this webpack feature was more built to load dynamically part of the application and not as an internal mechanism for a node module dependency to load code on demand (but i could be wrong).
I looked at other projects like babel or react-router where the module is split in several package using lerna and yarn package. So i have tried to build the library with lerna with different packages:
my-library
core/
src/
index.js
another-package/
src/
index.js
I want the index.js file from core to call a method from index.jsfrom another-package only if needed and only if the node-module #my-library/another-package was installed. But i never found the solution to do it.
Is it possible to achieve this with ES5/ES6 with webpack/lerna or did i took the wrong approach?
UPDATE October 27TH
So after several tests, I was able to use Aram solution with a plain HTML/JS (https://github.com/PixelDuck/lerna-webpack/blob/main/a-react-app/src/client/test.html) but the solution is not working with a react app package with webpack https://github.com/PixelDuck/lerna-webpack/blob/main/a-react-app/src/client/App.js.
The code is available there: https://github.com/PixelDuck/lerna-webpack.
Open a terminal to my-lerna-library and run
yarn install
yarn link:all, this will create symbolic link for each packages
`yarn dev', this will create bundle and listen to changes
then open a new terminal to folder a-react-app:
yarn install
yarn link "my-lerna-library"
yarn link "#my-lerna-library/another-package"
`yarn dev``
a page will be open on http://0.0.0.0:3000 and you will see that module #my-lerna-library/another-package is not found.
If you open http://0.0.0.0:5000/test.html the plainJS test, everything is looking fine.
It seems that the issue is on the webpack side for the react app because when debugging the application i can see that the core package is looking to a library name my_lerna_library__WEBPACK_IMPORTED_MODULE_3__ which is not the one used by webpack when loading the other package _my_lerna_library_another_package__WEBPACK_IMPORTED_MODULE_2___default
__webpack_require__.r(__webpack_exports__);
/* harmony import */ var react__WEBPACK_IMPORTED_MODULE_0__ = __webpack_require__(/*! react */ "./node_modules/react/index.js");
/* harmony import */ var _App_css__WEBPACK_IMPORTED_MODULE_1__ = __webpack_require__(/*! ./App.css */ "./src/client/App.css");
/* harmony import */ var _App_css__WEBPACK_IMPORTED_MODULE_1___default = /*#__PURE__*/__webpack_require__.n(_App_css__WEBPACK_IMPORTED_MODULE_1__);
/* harmony import */ var _my_lerna_library_another_package__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(/*! #my-lerna-library/another-package */ "../my-lerna-library/packages/another-package/dist/index.bundle.js");
/* harmony import */ var _my_lerna_library_another_package__WEBPACK_IMPORTED_MODULE_2___default = /*#__PURE__*/__webpack_require__.n(_my_lerna_library_another_package__WEBPACK_IMPORTED_MODULE_2__);
/* harmony import */ var my_lerna_library__WEBPACK_IMPORTED_MODULE_3__ = __webpack_require__(/*! my-lerna-library */ "../my-lerna-library/packages/core/dist/index.bundle.js");
/* harmony import */ var my_lerna_library__WEBPACK_IMPORTED_MODULE_3___default = /*#__PURE__*/__webpack_require__.n(my_lerna_library__WEBPACK_IMPORTED_MODULE_3__);
In your my-lerna-library > package:-
(1) another-package package.json file replace with this code
{
"name": "#my-lerna-library/another-package",
"private": true,
"version": "1.0.0",
"scripts": {
"dev": "webpack --watch --devtool inline-source-map --mode development",
"build": "webpack --mode production"
},
"dependencies": {
"#my-lerna-library/core": "1.0.0"
}
}
and
(2) core package.json file replace with this code
{
"name": "#my-lerna-library/core",
"private": true,
"version": "1.0.0",
"scripts": {
"dev": "webpack --watch --devtool inline-source-map --mode development",
"build": "webpack --mode production"
}
}
and my-lerna-library package.json file replace workspaces like this,
"workspaces": {
"packages": [
"packages/**"
]
},
Then run command "yarn run dev". I thing this is work for you!!
Finally i was able to achieve what i want.
Code here: https://github.com/PixelDuck/lerna-webpack
So the idea was to set another-package webpack config to output library as 'global' and on core package, looking at this global variable with
function isMyLernaLibraryAnotherPackageDefined() {
return typeof myLernaLibraryAnotherPackage !== 'undefined';
}
testFromAnotherPackage() {
if (isMyLernaLibraryAnotherPackageDefined())
return new myLernaLibraryAnotherPackage.AnotherClass().test();
}
Now on the react app, if i am importing import '#my-lerna-library/another-package';then message and svg are displayed.
If i am commenting this line, module is not found and nothing is displayed
If you need a package with optional dependencies you can create a core package together with several feature packages (which are not even listed in peerDependencies). You may explicitly list those feature packages in optionalDependencies.
Also, you core package should be designed so that it does not necessary require feature packages but can correctly work with them if they're installed. For example this way https://stackoverflow.com/a/50841764/14451484.
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.
I want to create a plugin so that I can raw-load a certain type of file with parcel. Parcel docs states that:
Publish this package on npm using parcel-plugin- or #your-scope/parcel-plugin- prefixes, and it will be automatically detected and loaded as described below.
...
Any dependencies listed in package.json with these prefixes will automatically be loaded during initialization.
Since this is a one-time thing, I don't want to publish the code on npm as a plugin. How do I load my project-local plugin with parcel?
Thanks in advance.
Since I could not find a way to do this in a parcel way, I did this in an npm way:
I created a folder named local_modules (this can be anything you want.) Then created parcel-plugin-x inside local_modules. Inside that, I created my plugin as usual. I also created a package.json specifying the entry point main. You can specify the dependencies required for the module just like if this is a separate project (THIS IS!).
{
"name": "parcel-plugin-x",
"version": "0.1.0",
"description": "Parcel plugin x",
"main": "index.js",
"devDependencies": {
},
"dependencies": {
}
}
Directory structure:
project-folder---local_modules---parcel-plugin-x
|---package.json |
|---index.js
|---package.json
Then I ran npm i --save-dev .local_modules/parcel-plugin-x inside the project-folder. It adds the line "parcel-plugin-x": "./local_modules/parcel-plugin-x", to the root package.json. This is the standard way of loading local modules in npm. And everytime you make changes to the plugin, you have to run npm upgrade. You should also increase the version of your plugin, too. This copies the plugin to node_modules and install dependancies.
According to the parceljs docs:
Any dependencies listed in package.json with these prefixes will
automatically be loaded during initialization.
now it works! :)
I did something similar, but with npm link.
In plugin folder (parcel-plugin-x) just run: npm link.
In the project folder using the plugin:
Link to parcel-plugin-x: npm link parcel-plugin-x
In package.json file, manually add the dependency to parcel-plugin-x
package.json
"devDependencies": {
"parcel-plugin-x": "^0"
}
Each time you make changes to the plugin, you don't have to run npm upgrade, but you might have to remove .cache folder created by parcel, because parcel will skip processing cached assets.
I think you can do this with the workspaces option in package.json: https://docs.npmjs.com/cli/v7/using-npm/workspaces
This library seems to be implementing it: https://github.com/astegmaier/stackoverflow-parcel-namer
I'm trying to include parse-react into my React Native project, but when running the app I'm getting the error in XCode and simulator:
Unable to resolve module ./lib/react-native/ParseReact.js from /Users/Corey/Work/example_app/node_modules/parse-react/react-native.js: Unable to find this module in its module map or any of the node_modules directories under /Users/Corey/Work/example_app/node_modules/parse-react/lib/react-native/ParseReact.js and its parent directories
I've included the two packages as such:
import Parse from 'parse/react-native';
import ParseReact from 'parse-react/react-native';
Looking in the node_modules/parse-react folder, the lib directory doesn't contain a react-native directory, but it does have the browser directory. I'm not sure if this is the problem or not, or how I'd go about getting that if it is.
I'm using react 0.14.7, react-native 0.21.0, parse 1.6.14, and parse-react 0.5.1.
I've had the same problem. I'm leaving my package.json here. Install accordingly, and you should be able to include parse modules into your project.
{
"name": "commonDemo",
"version": "0.0.1",
"private": true,
"scripts": {
"start": "node node_modules/react-native/local-cli/cli.js start"
},
"dependencies": {
"parse": "^1.8.1",
"parse-react": "^0.5.0",
"react-native": "^0.20.0"
}
}
Let me know if this works. Ideally, you should be able to include parse modules into your project using latest react-native release. But if using parse is absolutely necessary for your project, use this package.json.
To call Parse.initialize() use this-
var Parse = require('parse/react-native');
To call cloud functions and other functionality, use this-
var ParseReact = require('parse/react-native').Parse;
Look at the parse-react github README page. It says it works with version 1.6.14 of parse. It also says that 1.7 and 1.8 breaks compatibility. I had the same problem and downgrading to 1.6.14 solved the issue.
npm install parse#1.6.14 --save