Let's say I want to use Immutable in my project (or any given npm package). I have npm installed it, so it is in node_modules. Of course, it has CommonJS exports there. I, however, want to use es6 modules in my project.
I am using Webpack to compile it all together, with the 6to5-loader to deal with es6 module syntax.
In my source file, I say import Immutable from 'immutable'; --- but this causes a problem because the es6 import is looking for an es6 default to have been exported, which isn't the case (for Immutable or probably almost any other npm package). The compiled code ends up looking like this: var Immutable = require('immutable')["default"]; --- which of course throws an error, since there is no default property to find.
Can I consume the npm packages with es6 modules?
Babel.js contributor here. You're looking for the following:
import * as Immutable from 'immutable';
// compiles to:
var Immutable = require('immutable');
Interactive demo
Note: This is with either the common or commonInterop modules option. For others, see: https://babeljs.io/docs/usage/modules/
Just figured it out. (The solution is tool-specific --- but es6 modules only exist now insofar as they are tool-enabled, so I think that's enough of an "answer".)
6to5's default module transpilation uses the common option, which results in the very problem I griped about above. But there is another option: commonInterop --- which must have been built to deal with exactly the situation I'm dealing with. See https://6to5.github.io/modules.html#common-interop
So three cheers for 6to5.
Related
to sum up my circumstances:
I am running everything locally
I am using flask in the backend within a virtual environment
Goal: build a socket connection between Flask Backend and JS Frontend
PROBLEM: the problem is in the Frontend which is based on JS where I can't import the modules I got with npm
I am importing the modules as follows:
import { io } from "socket.io-client"
import { Hands } from "/#mediapipe/hands"
I also tried different import variants such as import * as io from "socket.io-client" and I also tried importing directly files as follows: import {io} from "socket.io-client/dist/socket.io", but all without success as these lead to "not found" errors.
I am sure that I installed them correctly with npm as I can see them in the folder structure, but the es6 imports are throwing an error as follows:
Failed to resolve module specifier "socket.io-client". Relative references must start with either "/", "./", or "../" - To solve this I tried adding slashes to different places like in the html tag where I include the script I tried transforming "type="module"" to "type="/module"" as recommended somewhere online, but without success. Also building direct references in the imports like "./node_modules/socket.io-client" do not work as it states that the file/folder is not found.
The problem must be the usage of the imports as everything works when I use Content Delivery Networks which also lets me assume that the version of the packages is not the problem as the version I get from the CDN is the same, but still the versions I use:
socket.io-client: 4.6.0
#mediapipe/hands: 0.4.1675469240
Flask: 2.2.3
Flask-SocketIO: 5.3.2
npm: 8.19.3
node: 16.19.1
My folder structure is as follows:
venv
main.py
templates
index.html
static
node_modules (includes socket.io-client and #mediapipe/hands)
js
main.js (the js file where the problem occurs)
package.json
I read a few times that the usage of "Webpack" is recommended, but I would like to skip that currently as I am not very familiar with that, so one question would also be: is it necessary to use it?
What can I possibly do wrong or how can I track my problem when it is about the import of es6 modules?
I would appreciate any help. Thanks in advance!
I could solve my problem for the socket.io-client package:
For the socket.io-client I imported a specific file directly although I do not really know why it worked as follows:
import { io } from './node_modules/socket.io-client/dist/socket.io.esm.min.js'
For the mediapipe package I still could not import the module in my js file directly and I am still relying on CDN. I tried the same thing in the same way by using:
import * as Hands from './node_modules/#mediapipe/hands/hands.js'
This, at least, does not result in an error, but the usage of "Hands" in this case is unclear to me as there is also no documentation for this use case in the mediapipe-js documentation. I could not directly import the {Hands} function as it resulted in an error saying "there is no function Hands in that path"
In the Jest tests for my React app in WebStorm, the following line
const { createMemoryHistory } = require("history");
has the following warning:
Module is not listed in package.json dependencies
The tests run as expected, they pass and fail as expected. createMemoryHistory works. And when I hover on history WebStorm actually shows me the documentation for the library.
(strike this:) But history is a native JS library, like fs, is it not? How do I fix this pesky warning?
UPDATE: Okay, I understand that fs is not a native JS library, it's a core node.js module. I was wrong and thanks for setting me straight on that.
I see that my package-lock.json does include an entry for "node_modules/history". It looks like it's two indents deep, but the lockfile is too complex for me to really tell, or get breadcrumbs, or fold the branch to see where this line falls in the tree.
So I guess the real question is, Webstorm is saying that I don't have the dependency, but the lockfile implies that I do. Unless I'm misunderstanding further.
Again, how do I fix this pesky warning? (or what other fact am I missing? Remember, everything does actually work).
fs is a core Node.js module, i.e. its code is compiled into Node.js binary and doesn't have to be installed. history library is a usual NPM module that is not a part of Node.js core and has to be added with npm i history(see https://github.com/remix-run/history/blob/main/docs/installation.md). The IDE just tells you that you are importing a module that is not listed among dependencies in your package.json
I'm using WebStorm 2017.1.3, although also tried with latest EAP, and i can't get import from statement to work. I just keep getting the following error:
import Utils from './utils'
^^^^^^
SyntaxError: Unexpected token import
In my packages.json i have babel-cli, babel-preset-env and babel-preset-es2015 defined. I have followed various blog posts and videos but still get same error.
ES6 is enabled in settings and i tried adding Babel file watch as per documentation but nothing seems to work. This feels like it should be a lot easier and just work, so i must be missing a important part of the jigsaw.
Does anyone have a working step by step, from fresh project, how to guide in configuring webstorm to work with import ?
Some places say use file watch, others say just to change project configuration interpreter to use babel-node. Other say must use Gulp... very confusing.
Thank you.
fLo
To make things clear: this is not about configuring WebStorm, error comes from Node.js interpreter that runs your code. Node.js still doesn't support ES6 modules natively (actually, no JavaScript runtime currently supports them - ECMAScript does not define a "Loader" specification which determines how Modules are inserted into the runtime. The Loader spec is being defined by WHATWG, but is not yet finalized). So, to get ES6 imports/exports accepted, you need using transpilers. Current industry standard is Babel
The most simple way to make it work is the following:
install babel in your project using npm install --save-dev babel-cli babel-preset-env
create a .babelrc file in project root dir:
{ "presets": ["env"] }
in your Node.js Run configuration, pass -r babel-register to Node:
With this configuration, your code will be transpiled on-the-fly by Babel, no file watchers, etc. are needed
I'm writing an Ember.js application using Ember Cli, and I want to include a non-bower dependency - basically a dependency from my vendor folder.
The instructions on doing so is telling me to add the following line into my ember-cli-build.js file:
app.import('vendor/dependency-to-include.js');
That would work fine with a normal ES5 flavored dependency, but what if I want to add a dependency written in ES6?
Right now it just delivers it to the browser untouched, which produces an error like:
Uncaught SyntaxError: Unexpected reserved word
because my ES6 flavored dependency uses the following syntax:
import Util from './util
I'm guessing that I need to tell ember-cli-build to transpile this particular dependency before passing it on to the browser, but how do I go about doing that?
Thanks
For transpiling imported dependencies you need to run the imported file(s) through the broccoli addon broccoli-babel-transpiler. For a basic example, checkout this file: https://github.com/thefrontside/ember-impagination/blob/2fa38d26ef1b27a3db7df109faa872db243e5e4c/index.js. You can adapt this addon to an in-repo addon for your project.
See this link for the background discussion and #rwjblue and #cowboyd on the actual fix: https://github.com/ember-cli/ember-cli/issues/2949
Are you currently including Babel within your project? I would have thought that it checks your vendor directory the same as it does everything else and converts the ES6 code to ES5.
The other option would be to just convert the file to ES5 manually whenever you need to include a vendor file with ES6 syntax. Not necessarily ideal, but if it's a static file then it's something you'll need to do once and then forget about.
So this is a really basic question. In all my blueprinted files, I see import statements such as:
import DS from 'ember-data';
Now I know that the build process is finding these in the vendor directory where bower installed them. Recently, I added moment.js, and I'd like to create a helper using it. However, there must be an additional naming convention that's being used because I can't simply
import moment from 'moment';
-- it claims it cannot find it in the tree merger. What is the right way to tell Broccoli where to find things when I want to import them?
Here is how I got things to work.
Install moment.js using bower install
Add the following line in Brocfile.js
app.import('vendor/moment/min/moment.min.js');
In your code, you do NOT have to import moment as it is NOT a ES6 module. You can call moment directly. For example,
var currDate = moment();
In the files where you use moment, don't forget to add the below comment as the first line of your file. You need to do this to avoid the jshint errors shown by ember-cli when you build the code
/* global moment:true */
Hope this helps!