I have a requirement where I am trying to use the Babel plugin "preset-env". This plugin compiles my NextJS project from ES6 to ES5. I have created the .babelrlc file as suggested by NextJS documentation and added my plugin like this:
{
"presets": ["next/babel"],
"plugins": ["#babel/preset-env"]
}
When I try to run my project locally I get this error:
error - ./node_modules/next/dist/client/router.js
Error: Cannot find module '#babel/plugin-preset-env' from '/Users/agastya/Local/testcap/Sample-proj'
- If you want to resolve "#babel/preset-env", use "module:#babel/preset-env"
- Did you accidentally pass a preset as a plugin?
NextJS documentation says "Next.js includes the next/babel preset to your app, which includes everything needed to compile React applications and server-side code. ".
It would be great if someone can explain where/what is the right approach to fix this.
You have to do the following:
// .babelrc file, also could be babel.config.js
{
"presets": [
[
"next/babel",
{
"preset-env": {},
"transform-runtime": {},
"styled-jsx": {},
"class-properties": {}
}
]
],
"plugins": []
}
Taken from: https://nextjs.org/docs/advanced-features/customizing-babel-config
Related
My ultimate goal is to get e2e and unit code coverage for my Vue 3 app using Cypress in my CI/CD pipelines.
However, when using the following configuration in my babel.config.js I get a flood of repeated error messages that read don't know how to turn this value into a node at transformFile.next (<anonymous>) for each Vue file in my app that uses <script setup>.
babel.config.js
module.exports = {
presets: [
'#vue/cli-plugin-babel/preset',
],
plugins: [
['babel-plugin-istanbul', {
extension: ['.js', '.vue']
}]
],
};
package.json
"dependencies": {
"core-js": "^3.6.5",
"vue": "^3.0.0"
},
"devDependencies": {
"#vue/cli-plugin-babel": "~4.5.15",
"#vue/cli-plugin-eslint": "~4.5.15",
"#vue/cli-service": "~4.5.15",
"#vue/compiler-sfc": "^3.0.0",
"babel-eslint": "^10.1.0",
"babel-plugin-istanbul": "^6.1.1",
"eslint": "^6.7.2",
"eslint-plugin-vue": "^7.0.0"
},
App.vue
<script setup>
import HelloWorld from './components/HelloWorld.vue'
</script>
My concern is that the plugin doesn't know how to handle Vue 3's script setup syntax.
Sadly, the only how-to guides I can find online are for Vue 2 or React apps.
https://docs.cypress.io/guides/tooling/code-coverage#Using-NYC
https://vuejsdevelopers.com/2020/07/20/code-coverage-vue-cypress/
So my question is: what can I do to get my app to transpile while using babel-plugin-istanbul and script setup?
Steps to Reproduce:
Create a new Vue 3 app with vue-cli-service
Install babel-plugin-istanbul in your dev dependencies
Configure your babel.config.js as shown above
Convert your App.vue to use <script setup>
Run npm run serve
Expected behavior:
The app transpiles with no errors
Actual behavior:
Transpilation failure with don't know how to turn this value into a node errors for App.vue.
The resolve is to use istanbul in the babel config (as given in Cypress docs).
The cause isn't apparent, without <script setup> the full name babel-plugin-istanbul works ok.
plugins: [
['istanbul', {
extension: ['.js', '.vue']
}]
],
I am solving same problem and I can point out two things:
The problem is in babel.config.js file especially with .vue extension, when you remove it works, but for me it instrument all files.
I have a feeling another problem is with CLI versions plugins. I don't have problem to run the cypress code coverage plugin with older packages.
If add extension:['.vue'] in bable.config.js configuration, getting below error.
src/pages/somefile.vue?vue&type=script&setup=true&lang=js
Module build failed (from ./node_modules/#vue/cli-plugin-babel/node_modules/babel-loader/lib/index.js):
Error: src/pages/somefile.vue: don't know how to turn this value into a node
I ran into this as well. It turned out to be a bug in the istanbul-lib-instrument package, which was fixed in this PR: https://github.com/istanbuljs/istanbuljs/pull/662
If you upgrade your installed copy of istanbul-lib-instrument to 5.2.1 (i.e., npm update istanbul-lib-instrument) the issue should go away.
I have an ES6 React app that is being bundled with webpack and using babel. I am configuring babel-preset-env, for node everything is working perfect, but for browser the size of my build is not changing regardless the target percentage. The size is the same when the interval is >1 or when its 90%.
The webpack version is 1.13.1, my babel version 6.26.0 and babel-preset-env version is 1.6.1
I have this in my .babelrc
{
"presets": [
"es2015",
"stage-0",
"react",
[
"env",
{
"targets": {
"node": "9.4.0",
"browsers": [
">1%"
]
}
}
]
],
"plugins": [
[
"transform-class-properties",
"transform-runtime",
"transform-decorators-legacy",
"react-intl",
{
"messagesDir": "./build/messages",
"enforceDescriptions": false
}
]
]
}
When you use babel-preset-env it will decide, based on the list of browsers your target, to include only the necessary babel transforms.
It is an alternative to es2015 and stage-0, and including those presets along with env is counterproductive, as the transforms included in those presets will be applied whether they're needed or not.
It also depends on how you use babel-polyfill. Set it as import 'babel-polyfill' at the beginning of your JavaScript entry file, and babel-preset-env will replace the import with individual imports with only the polyfills needed for the browsers you target.
I am not sure if it works that way if you include babel-polyfill as part of the Webpack entry option, e.g.:
js
entry: {
myentry: ['babel-polyfill', 'js/index.js']
}
Hope this will help you get that bundle size down!
P.S. I'm aware the babel-preset-env documentation is not the clearest when it comes to describing what you need to do.
Make sure you have import "#babel/polyfill"; in your index.js.
Also, make sure you only import it once.
If you have something like this
entry: ["#babel/polyfill", path.join(__dirname, "./src/index.js")],
in your webpack config, move the polyfill, so it should look like
entry: path.join(__dirname, "./src/index.js")
I'm new to react, babel, and antd.
I installed react and started a project using create-react-app.
I installed antd (ant.design). It suggests using babel-plugin-import, so I installed that too.
If I interpret it right, the usage documentation for babel-plugin-import says to put this in a .babelrc file:
{
"plugins": [
["import", {
"libraryName": "antd",
"style": true
}]
]
}
I'm having trouble getting it to work. My web console still has the warning:
You are using a whole package of antd, please use
https://www.npmjs.com/package/babel-plugin-import to reduce app bundle
size.
I didn't have a .babelrc file in my project's directory, so I created one with the above contents and restarted my server (npm start). That didn't work, so I created one in myProject/node_modules/babel_plugin_import but that doesn't work either.
Where is that code snippet supposed to go?
At the bottom of https://github.com/ant-design/babel-plugin-import it says
babel-plugin-import will be not working if you add the library in
webpack config vender.
But I don't know what that means.
I asked another question here: How to get antd working with app created via create-react-app?
Maybe this problem has something to do with my project created via create-react-app??
[Update 2018-02-06: The answer is still correct, but there is a better alternative now, which is to use react-app-rewired. This is also documented in the link.]
You need to follow the instructions in https://ant.design/docs/react/use-with-create-react-app#Import-on-demand to a T.
You should not create ant .babelrc files or similar. When using CRA all babel config is handled inside the webpack config files.
First clean up the config files you created, and make sure you have babel-plugin-import installed.
Then eject your app: npm run eject
This will give you a config folder with 2 webpack config files for dev/prod environments.
Open those files and locate the place where you need to insert the plugins property as documented on the instructions page.
Just add what babel-plugin-import documentation says, but remember if you're using CRA, you cannot change babel configuration directly without ejecting the project.
If you don't want to eject, you can use #craco/craco, and put the babel configuration inside of it like this:
/* craco.config.js */
module.exports = {
babel: {
presets: [],
plugins: [
[
"import",
{
libraryName: "antd",
style: true, // or 'css'
},
],
],
loaderOptions: {
/* Any babel-loader configuration options: https://github.com/babel/babel-loader. */
},
},
};
Dont forget to change your scripts (more details in craco docs):
/* package.json */
"scripts": {
- "start": "react-scripts start",
+ "start": "craco start",
- "build": "react-scripts build",
+ "build": "craco build"
- "test": "react-scripts test",
+ "test": "craco test"
}
I am trying to set up Jest on a React based project which uses ES6 modules. However I seem to be having issues with ES6 modules, I am using babel-jest and believe I have this set up properly (Jest detects it automatically).
Jest doesn't seem to have a problem using ES6 imports however as soon as it hits on an import statement within one of the imported modules it chokes. It's as if it is only transpiling the initial test script and not any of the imported modules. I have tried various configurations and tried searching Google with no luck. Running tests without any imports works fine.
Here is the error:
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){import Predications from './predications';
^^^^^^
SyntaxError: Unexpected token import
Here are the relevant bits of config:
jest.conf.json
{
"testRegex": "\/test\/spec\/.*\\.js$",
}
.babelrc
{
"presets": ["es2015", "stage-0", "react"]
}
Test script
import React from 'react';
import { mount, shallow } from 'enzyme';
import Slider from 'react-slick';
import Carousel from '../../client/components/carousel/carousel.js'; // test chokes on when I include this module
describe('carousel component', () => {
it('is a test test case', () => {
expect(1 + 2).toEqual(3);
});
});
Update:
As suggested, I have tried running the test without jest.conf.js, however the testRegex is needed in order for Jest to find my tests, I tried moving tests to the default test directory and they still fail.
I would like to clarify that tests themselves are running fine, the issue seems to be where one of my imported modules uses ES6, in my example above, if I don't import my carousel component the test runs fine, as soon as I import that the test chokes on the import statement within that file. It seems as though the imported modules are not getting transpiled.
Update #2
After some investigation it appears the issue is that babel is not transpiling ES6 within node_modules. I have created an example repo to demonstrate this here: https://github.com/jamiedust/babel-jest-example
I understand that third party modules should be handling their own transpiling, however we have a number of modules which are hosted on our own npm registry and are re-used between projects, in these cases Webpack handles transpiling, for the Jest tests we need these node_modules to be transpiled by Babel, or a way of leveraging our webpack set up to do this for us.
Solution
Add the following config in package.json (or Jest config file).
"jest": {
"transformIgnorePatterns": [
"/node_modules/(?!test-component).+\\.js$"
]
}
By default any code in node_modules is ignored by babel-jest, see the Jest config option transformIgnorePatterns. I've also created a PR on your example repo, so you can see it working.
While this works, I've found it to be extremely slow in real applications that have a lot of dependencies containing ES modules. The Jest codebase has a slightly different approach to this as you can find in babel-jest transforming dependencies. This can also take much longer on Windows, see Taking 10 seconds on an empty repo.
If doing "unit" testing, mocking is probably the better way to go.
You could try adding the transform-es2015-modules-commonjs plugin to your babel config file for testing only. Here is an example config file which tells babel to transpile modules only when in a testing environment. You can put it underneath your presets:
{
"presets": [
"react",
["es2015", {"modules": false, "loose": true}]
],
"env": {
"test": {
"plugins": ["transform-es2015-modules-commonjs"]
}
}
}
You can read about the plugin here:
https://www.npmjs.com/package/babel-plugin-transform-es2015-modules-commonjs
Then, when running your Jest tests on the command line specify NODE_ENV=test (you may need to add the --no-cache flag to the command the first time after making the change to the babel config because Jest caches babel output, but after that you can leave it off:
NODE_ENV=test jest --no-cache
I learned about this issue in a React seminar by Brian Holt at Frontend Masters. https://frontendmasters.com/courses/
faced the same issue, followed the steps to resolve,
install babel-jest
in jest config add this configuration
transform: {
'^.+\\.js?$': require.resolve('babel-jest')
}
make sure you have babel.config.js present (your config might be different than provided below)
module.exports = {
"env": {
"test": {
presets: [
[
'#babel/preset-env',
{
targets: {
node: 'current',
},
},
],
]
}
}
};
I faced the same problem (node_module not transpiled by babel-jest), without being able to solve it.
Instead, I finally succeed by mocking the node_module, like described here https://facebook.github.io/jest/docs/manual-mocks.html
NB: setting mocks in __mocks__ subfolders did not work for me. So I passed the mock as the second parameter of the jest.mock() function. Something like :
jest.mock('your_node_module', () => {})
Another possible cause. Babel now ignores your .babelrc inside node_modules and uses the one provided by the dependency. If you have control of the dependency you would have to add a .babelrc to it and babel would use those settings for it.
this can cause problems though if your dependency and your project use different babel versions or modules.
I am building an EmberJS application with the great help of ember-cli, which is great, but I have an error and I cannot find what I am doing wrong.
Here is what I do in my broccoli file:
app.import('vendor/underscore/underscore.js', {
exports: {
"underscore": [
"underscore"
]
}
});
and then in one of my controllers:
import _ from "underscore";
ember-cli builds my application.
But when I go to the controller using underscore, I get the error:
Error: Could not find module underscore.
What am I doing wrong?
Try:
app.import({
development: 'vendor/underscore/underscore.js',
production: 'vendor/underscore/underscore.min.js'
}, {
'underscore': [
'default'
]
});
This will at least give "import _ from 'underscore';" a chance to work. If you choose an AMD or ES6 version of underscore/lodash, list which modules you wish to import with 'default'.
EDIT:
Is it crucial that you use underscore? Why I ask, I'm using lodash with one Ember-cli project, and it is working fine.
Console> bower install lodash --save
then in Brocfile:
app.import({
development: 'vendor/lodash/dist/lodash.js',
production: 'vendor/lodash/dist/lodash.min.js'
}, {
'lodash': [
'default'
]
});
//or:
app.import('vendor/lodash/dist/lodash.min.js');
As for underscore - there was an issue with devDependencies not being bundled, of which underscore is one.
I got this from locks on #emberjs IRC.
https://github.com/ef4/ember-browserify
In your project:
npm install --save-dev ember-browserify
npm install --save-dev underscore
In your controller:
import _ from "npm:underscore";
Then you can use _. For example: _.each([1,2,3], alert);. I took everything out I had manually added to brocfile and package.json. Apparently this will do it for you. Crazy!
In recent versions of ember (I am using 2.11) it is possible to load AMD in UMD wrappers using
app.import('bower_components/js-md5/js/md5.js', {using: [{
transformation: 'amd', as: 'js-md5'
}]});
And in your code
import md5 from 'js-md5';
In your case of underscore it should look like:
app.import('vendor/underscore/underscore.js', {using: [{
transformation: 'amd', as: 'underscore'
}]});