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ES6 module, what counts as the first import?

Here's my module:
console.log("module imported");
export function call(){};
In main.ts:
import * as mod from './module';
// other code that doesn't use mod.
I would have expected this to log "module imported" to the console. In fact, the example seems pretty much the same as this one. And they say:
A module code is evaluated only the first time when imported
But there are no console logs. However, after the following edits to main.ts the log message appears:
import * as mod from './module';
if(false){
mod.call();
}
It would make sense if only the first time the module is actually used counted as the first import. But here the log message seems to be based on static analysis alone. The code path that uses the module is never executed.
How does this work? What counts as the first import of an ES6 module?
Also, my gut feeling says that this might be about the bundler. Does it optimize away an unused import like this? I'm running these code snippets in a react app, created with:
npx create-react-app my-app --template typescript
cd my-app
# add the module and import it to index.tsx
npm i
npm run start
# browser opens, check the console
On the other hand, the typescript react app also has imports like './index.css' and they are only there for the bundler to package them. It seems common to import something only for its side-effects.
I have searched for related questions but so far haven't found something with this specific problem:
Run ES6 code only if module is executed directly
`if __name__ == '__main__'` equivalent in javascript es6 modules
In browser JS code that imports from ES6 module is not executed
The last of these looks like a duplicate, but it is about a specific syntax error in the module resolution.

Your guess is correct, it's happening because of bundler. Its a feature of bundler known as Dead code elimination. To know more about it, search for Tree Shaking or Dead code elimination.
If you are not going to use anything from imported module, source code of module will not be included in your build.
I think create-react-app use Webpack for bundling. If you want to disable the feature, starting the app in development mode may solve it. BTW, its good to remove unused code while building.

"ERROR in xx.js from UglifyJs Invalid assignment" when importing a module into another module

I cannot post exact code due to NDAs, so I will do my best.
Javascript is not my string suit, but I took it up for my team.
Background:
I built a module which basically will perform a very simple task and can be imported as a dependency in other projects and then added into the project by adding the tag.
I wanted to keep this as lightweight as possible and let the app which was adding it in do the heavy lifting and have the imports to run and compile Angular code.
Code for SimpleApp:
Everything seems to work fine except for places marked with /* Potential Issue */
Within the simple module, I have a few file:
simpleApp.js -- the main js file which does the work necessary
simpleApp.html -- the html of simpleApp.js
innerProvider.js -- a module.service which does some work when called from the simpleApp.js -- this import seems to be the issue causer.
All within the companySimpleApp package:
simpleApp.js:
import angular from "angular"
/* I believe this to be the issue */
import innerProviderModule from "./pathToFile/innerProvider /* Potential Issue */
/* Potential Issue */
angular.module('simpleApp', [innerProviderModule]).component('simpleComponent, {
controller: ['$scope, 'innerProvider', ..., function($scope, innerProvider, ...) {
/* does work */
}],
template: require("./simpleApp.html"),
bindings: {
bind1: '#',
bind2: '#'
}
simpleApp.html:
<div>
do stuff
call stuff
</div>
innerProvider.js:
import angular from "angular"
const innerProviderModule = angular.module('innerProvider', [])
.service('innerProvider', function (%http, ...) {
this.doWork = function (param1) {
retStmt = doSomething(param1)
return retStmt
}
});
export default innerProviderModule.name;
Everything here builds correctly and will do as is told. I am able to build this package as well as the one which uses it and have a working webpage with the simpleApp's services. However, this is when I host everything myself.
Code for Larger Service using SimpleApp:
In another project I have this listed as a dependency "simpleApp = 1.0" this may be different than expected due to my company's internal workings, but this works.
It appears in the node_module directory
I then have a module for the webpage which loads in simpleApp and has all of the other packages like angular, babel, uglify, webpack, etc:
/* Potential Issue */
import "companySimpleApp/simpleApp.js"
export default angular
.module("app", [otherDependencies, simpleApp])
.config(function ($stateProvider, $stuff){
someMappingsForUrls
});
...
<script src="../node_modules/companySimpleApp/simpleApp.js"></script>
...
and another html and js file which use the simpleApp
<div>
<simpleApp bind1='{{value}}'></simpleApp>
</div>
Error:
Now, everything will run fine on my localhost and I can fully use the larger service using SimpleApp site with the simpleApp. However, when I build this (npm run webpack) on the service using simpleApp, I get the following error even though everything seems to run fine on my localhost:
ERROR in bundle.js from UglifyJs
Invalid assignment [bundle.js:146461,67]
npm ERR! code ELIFECYCLE
npm ERR! errno 2
npm ERR! # webpack: `webpack -p`
npm ERR! Exit status 2
npm ERR!
npm ERR! Failed at the # webpack script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
........
The code seems to build when I remove the import innerProviderModule from "./pathToFile/innerProvider from simpleApp.js but I then get an error saying that innerProvider is an unresolved reference or something along the line.
What I am asking is for some help on why I may be seeing this error when I import the innerProviderModule I built. Do I need to add webpack and all that to my simpleApp project even though it all seems to run fine physically on my localhost?
Any help or ideas is very much so appreciated. Thanks!
Bumping this as I posted it late at night.
Edit: It seems to not like "=>" in the innerProvider which I have

I built the package which uses the simpleApp with 'webpack -p' which was not done on simpleApp. So, what it looked like that happened was that the simpleApp was not minified or something and didnt like a few lines in the provider code (ie: "=>", "let", etc...)
So instead of having the simpleApp have more dependencies, I simply wrote code which would pass webpack -p.
You should also be able to just remove the "-p" flag
Hope this helps someone.

VS code highlights jasmine functions in Angular 6

I've recently migrated to Angular 6.0. And VS Code highlights all jasmine functions as unknown. It works fine and runs tests successfully. How to let intellisense know about Jasmine?
In previous version some workaround worked:
import {} from "jasmine"
But it doesn't work any more.
Next import in test.ts also generates errors:
import 'jasmine';
Update: If I add "jasmine" to types in tsconfig.json - it does the trick. But it doesn't work with tsconfig.spec.json. I don't need this types in application bundle.

Try running npm i #types/jasmine and add "jasmine" to the types-array in the tsconfig.json file. I had the same issue and this worked for me.

Using Vue Design System in Nuxt is throwing errors about export in system.js

I am trying to get the components imported into a Nuxt project, following the steps here:
https://github.com/viljamis/vue-design-system/wiki/getting-started#using-design-system-as-an-npm-module
Nuxt does not have a main.js (everything is plugin based), so what I have done is create a "plugin" and then do the import code in there like so (Nuxt recommends this for other libraries too and works fine):
vue-design-system.js
import Vue from 'vue'
import system from 'fp-design-system'
import 'fp-design-system/dist/system/system.css'
Vue.use(system)
Then in my config I do (removed other code in config):
nuxt.config.js
module.exports = {
css: [
{ src: 'fp-design-system/dist/system/system.css', lang: 'css' }
],
plugins: [
{ src: '~plugins/vue-design-system', ssr: true }
]
}
When I run npm run dev in my theme, it builds, but I get a warning:
WARNING Compiled with 1 warnings warning in
./plugins/vue-design-system.js 7:8-14 "export 'default' (imported as
'system') was not found in 'fp-design-system'
Seems to have an issue with the generated system.js regarding the export (the command npm run build:system).
In my page on screen I get the following error when trying to use a component in the design system:
NuxtServerError Cannot find module
'fp-design-system/src/elements/TextStyle' from
'/Users/paranoidandroid/Documents/websites/Nuxt-SSR'
If I hard refresh the page, I then get another message:
NuxtServerError render function or template not defined in component:
anonymous
Any idea what's happening here? It would be really great to get this working somehow.
At this current time, I'm not sure if it's a Nuxt issue or a Vue Design System issue. I think the latter, just because the Nuxt setup I have right now is very bare-bones...so it's not something else causing this.
Thanks.
Repository on GitHub:
Here is the repo for my "theme", but in order to get this going, you will need to create a design system separate from this with the same name and follow the steps to use the design system as a local (file) NPM module.
https://github.com/michaelpumo/Nuxt-SSR
console.log of system (from the JS import statement)

As for your first error (""export 'default' (imported as 'system') was not found in 'fp-design-system'"), the UMD built JS from vue-design-system does not export a "default" object. But you can simply workaround the issue by importing it as:
import * as system from 'fp-design-system'
instead of:
import system from 'fp-design-system'
Then another issue comes quickly as you noticed in your comments: "window is not defined", due again to the UMD built JS that expects window to be globally available, instead of the usual trick to use this (which equals window in a browser). Therefore as it is, the build is not comptible with SSR.
You could however slightly rework the built JS by replacing the first occurrence of window by this, but I am not sure if the result will still work.
Most probably you should better keep this module for client rendering only.

It seems Vue is looking for the ES6 pattern for importing module, which you should use for external javascript modules/files.
in ES6 it is
export default myModule
in ES5 it was
module.exports = myModule
Hope it will help.

Ember load-initializers error: Could not find module `ember-load-initializers`

I'm having trouble updating an older Ember app.
I've ported the code into a new, empty ember app and installed the dependencies. I get no error when I serve the app, but when I inspect the browser console, I see that the app failed to launch.
Uncaught Error: Could not find module `ember/load-initializers` imported from `<my-app>/app`
I've seen a similar SO post that suggested this was caused by issues with ember-cli and jquery. link
However, that post is over a year old and I'm running an up-to-date version of ember along with an newer jquery library. Sure, it's no guarantee, but it seems a bit unlikely that this is still an issue for ember-cli.
My app/app.coffee file is pretty basic (no additions)
`import Ember from 'ember'`
`import Resolver from 'ember/resolver'`
`import loadInitializers from 'ember/load-initializers'`
`import config from './config/environment'`
Ember.MODEL_FACTORY_INJECTIONS = true
App = Ember.Application.extend
modulePrefix: config.modulePrefix
podModulePrefix: config.podModulePrefix
Resolver: Resolver
loadInitializers(App, config.modulePrefix)
`export default App`
From the console, I can verify that my app is using the expected jquery version:
$ Ember.$.fn.jquery
"3.2.0"
However, from the command line, I get a different version.
$ bower jquery -v
1.8.0
I'm not sure whether that's meaningful or a red herring.
At any rate, my ember-cli is fairly recent.
ember-cli: 2.12.0
I've added links to the package.json and bower.json files, in case they contain any clues.
At this point, I'm not really sure how to troubleshoot the issue. The depency

import Resolver from './resolver'
import loadInitializers from 'load-initializers'
Update those line app.js file and try it

If you haven't done this already, in the app.js, switch
import loadInitializers from 'ember/load-initializers'
over to
import loadInitializers from 'ember-load-initializers'
they changed the naming conventions of loadInitializers recently.