Develop Reference

Vue 3 component incorrectly initialized when module is `npm link`ed

Following is the entry point to my library, it generates a component with a dynamic tag:
// muvement.js
import { defineComponent, ref, onMounted, h } from 'vue';
const createMuvement = (tag) => {
return defineComponent({
name: `m-${tag}`,
setup(props, context) {
const root = ref(null);
onMounted(() => {
console.log(root.value);
});
return () => h(tag, { ...context.attrs, ref: root }, context.slots);
}
});
};
const muvement = (...tags) => {
const components = {};
tags.map((tag) => (components[`m-${tag}`] = createMuvement(tag)));
return components;
};
export { muvement };
It's expected to be consumed like so:
// Home.vue
<template>
<div>
<m-div>div</m-div>
<m-button>button</m-button>
</div>
</template>
<script>
import { muvement } from "muvement";
export default {
name: "Home",
components: {
...muvement("div", "button")
}
};
</script>
This works as expected when the library code is contained within the Vue app folder (assuming we are now importing from "#/components/muvement.js" instead of "movement").
That is:
-muvement-test-project (scaffolded with vue-cli)
- src
- views
- Home.vue
- components
- muvement.js
I've also published an alpha release that works fine when importing "muvement" after installing it directly from the npm registry (that is, npm install muvement instead of npm link muvement).
The Problem
During development, I want an app to test the library with that is separate from the library's directory.
I've used npm link to link the library to the test app (as I have done with many other projects in the past).
From /path/to/library
$ npm link
From /path/to/test/app
$ npm link muvement
So far so good. The module is available as a symlink in the test app's node_modules folder. So I import { muvement } from "muvement", run npm run serve, and... BOOM.
Everything explodes (see errors below). It's also probably worth noting that trying to import from the full path (i.e. C:/dev/npm/muvment/dist/es/index.js) results in the same issues as npm link does, so I don't think it has anything to do with the symlink directly.
This is what appears in the console:
For pretty much the entire day I have been trying to solve this one issue. I've seen several seemingly similar questions that were solved by settings Webpack's resolve.symlinks to false but that has no effect on my problem. I've read all through the docs and even Vue's source code (here is the offending line for those who are curious).
Since the warning suggests that the error is commonly attributed to async setup I thought maybe webpack was doing something weird that would make my code async. This doesn't seem to be the case as the call stack of both the working attempt and failed attempt are identical.
What's not identical is the scope.
Here is the scope for the example that is working:
And here is the failing one:
(Notice that the target parameter is null during the call to injectHook, which is obviously what prompts Vue to show a warning).
My question is, why does the location of the imported module make such a difference during the execution of the said module?
The library code and build setup are available here:
https://github.com/justintaddei/muvement
The test app is available here:
https://github.com/justintaddei/muvement/tree/example
If I've left out something important, please let me know in the comments. It's been a long day so I'm sure I've probably missed something.
Thank you.

The problem is your app is using two different vue dependencies under the hood - vue requires the same dependency to be used to keep track on reactivity, lifecycle, etc.
When you link a library npm/yarn will use that linked folder node_modules, but your app is using it's dependencies from it's node_modules.
When your app imports vue it will go app/node_modules/vue but when you import from your linked dependency it will be going to linked_dep/node_modules/vue.
app
node_modules
vue
linked library
node_modules
vue
One easy way to debug this issue is to change both vue dependency files with a console.log and check if the console is logging both.

How to best import "server-only" code in Next.js?

In the getServerSideProps function of my index page, I'd like to use a function foo, imported from another local file, which is dependent on a certain Node library.
Said library can't be run in the browser, as it depends on "server-only" modules such as fs or request.
I've been using the following pattern, but would like to optimize it. Defining foo as mutable in order to have it be in scope is clunky and seems avoidable.
let foo;
if (typeof window === "undefined") {
foo = require("../clients/foo");
}
export default function Index({data}) {
...
}
export async function getServerSideProps() {
return {
props: {data: await foo()},
}
}
What would be the best practice here? Is it somehow possible to leverage ES6's dynamic import function? What about dynamically importing within getServerSideProps?
I'm using Next.js version 9.3.6.
Thanks.
UPDATE:
It seems as if Next.js's own dynamic import solution is the answer to this. I'm still testing it and will update this post accordingly, when done. The docs seem quite confusing to me as they mentionn disabling imports for SSR, but not vice versa.
https://nextjs.org/docs/advanced-features/dynamic-import

When using getServerSideProps/getStaticProps, Next.js will automatically delete any code inside those functions, and imports used exclusively by them from the client bundle. There's no risk of running server code on the browser.
However, there are a couple of considerations to take in order to ensure the code elimination works as intended.
Don't use imports meant for the server-side inside client-side code (like React components).
Ensure you don't have unused imports in those files. Next.js won't be able to tell if an import is only meant for the server, and will include it in both the server and client bundles.
You can use the Next.js Code Elimination tool to verify what gets bundled for the client-side. You'll notice that getServerSideProps/getStaticProps gets removed as do the imports used by it.

Outside of getServerSideProps/getStaticProps, I found 2 fairly similar solutions.
Rely on dead code elimination
In next.config.js:
config.plugins.push(
new webpack.DefinePlugin({
'process.env.RUNTIME_ENV': JSON.stringify(isServer ? 'server' : 'browser'),
}),
);
export const addBreadcrumb = (...params: AddBreadcrumbParams) => {
if (process.env.RUNTIME_ENV === 'server') {
return import('./sentryServer').then(({ addBreadcrumb }) => addBreadcrumb(...params));
}
return SentryBrowser.addBreadcrumb(...params);
};
Note that some for reason I don't understand, dead code elimination does not work well if you use async await, or if you use a variable to store the result of process.env.RUNTIME_ENV === 'server'. I created a discussion in nextjs github.
Tell webpack to ignore it
In next.config.js
if (!isServer) {
config.plugins.push(
new webpack.IgnorePlugin({
resourceRegExp: /sentryServer$/,
}),
);
}
In that case you need to make sure you will never import this file in the client otherwise you would get an error at runtime.

You can import the third party library or a serverside file inside getServerSideProps or getInitialProps since these functions run on server.
In my case I am using winston logger which runs on server only so importing the config file only on server like this
export async function getServerSideProps (){
const logger = await import('../logger');
logger.info(`Info Log ->> ${JSON.stringify(err)}`);
}
You can also import library/file which has default export like this
export async function getServerSideProps(context) {
const moment = (await import('moment')).default(); //default method is to access default export
return {
date: moment.format('dddd D MMMM YYYY'),
}
}

What is the equivalent of module.exports for ES6 Modules?

I have an existing package written in JavaScript that I'm trying to convert to TypeScript. My question is, what is the equivalent of module.exports for ES6 Modules?
For example if I have the following code:
module.exports = function () {
console.log("Hello World");
};
The only way I have found to do this in ES Modules is by doing something like the following.
const myFunc = function () {
console.log("Hello World");
};
export default myFunc;
// OR
export { myFunc };
Of course, this is not the same thing as module.exports = //....
Which leads to this problem. When I run this through TypeScript and get the outputted code, users of the package will either need to use an import defaultExport from "module-name"; statement (which isn't bad), or instead of being able to access it using require("module-name") they will have to use require("module-name").default (if they are using standard JS, not TypeScript). Which obviously is a breaking API change for standard JavaScript users.
Obviously, the goal here is to have no breaking API changes (and require no changes for customers code).
One more requirement to any solution. In other places in the package I need to be able to export a lot of different files as one object. So in the past I've been doing:
module.exports = {
"thing1": require("./a.js"),
"thing2": require("./b.js")
};
So I need to be able to export this as normal without requiring the user to do thing1.default. This one so far seems like the easier requirement since I'm exporting an object which ES Modules seems to handle really well. It's when you are exporting a singular (non-named) expression that it gets really tricky.
Is there a way to do this without having to make this a breaking change to the API?

The solution here is to use the TypeScript export = command. This allows you to use either require or import with the module.
export = function () {
console.log("Hello World");
};
import myModule from "./lib/myModule";
// OR
const myModule = require("./lib/myModule");
For more information the TypeScript documentation has a guide about Migrating from JavaScript, and specifically a section called Exporting from Modules.

Typescript recommends not to rewrite your code, but instead to configure it to allow js modules.
When we were working on converting a very large app from js to TS, we took the position of writing new code in TS, and slowly converting js into ts (but not spend a whole lot of time just converting).
We needed to enable few options in the tsconfig.json, such as :
{
...,
"compilerOptions" : {
...
"moduleResolution": "node",
"allowJs": true,
...
},
"include" [
"path/to/my/js",
]
}
you also need to update your webpack.config.js:
module.exports = {
// ... my settings
resolve: {
// Add '.ts' and '.tsx' as resolvable extensions.
extensions: ["", ".webpack.js", ".web.js", ".ts", ".tsx", ".js"]
},
}
You might also have to declare require as a function (if you are getting errors such as require is undefined):
declare function require(path: string): any;
more info is available here :
https://www.typescriptlang.org/docs/handbook/migrating-from-javascript.html

Most accurate replacement for module.exports in typescript is export default
export default {
"thing1": require("./a.js"),
"thing2": require("./b.js")
}
then you can use them like below
import myThings from '.....'

How do I manually include "#material/drawer" into my component?

I am trying to manually include the #material/drawer npm package into my Ember app. I tried following this guide but I'm running into some weird errors in my Chrome dev console:
Uncaught SyntaxError: Unexpected token *
Uncaught ReferenceError: define is not defined
The first is from the imported node_modules/#material/drawer/index.js file and the second is from my generated shim.
My component code:
import Component from '#ember/component';
import { MDCTemporaryDrawer, MDCTemporaryDrawerFoundation, util } from '#material/drawer';
export default Component.extend({
init() {
this._super(...arguments);
const drawer = new MDCTemporaryDrawer(document.querySelector('.mdc-drawer--temporary'));
document.querySelector('.menu').addEventListener('click', () => drawer.open = true);
}
});
In my ember-cli-build.js:
app.import('node_modules/#material/drawer/index.js');
app.import('vendor/shims/#material/drawer.js');
My generated shim:
(function() {
function vendorModule() {
'use strict';
return {
'default': self['#material/drawer'],
__esModule: true,
};
}
define('#material/drawer', [], vendorModule);
})();
What exactly am I doing wrong? It almost seems as though raw ES6 code got imported rather than compiled into my JS build output.
I also read this SO post but there are too many answers and I'm not sure which to do. It seems this specific answer is what I'm trying to do but not verbatim enough.

Creating a shim only ensures that ember-cli gets an AMD module, which you then can import in your app files.
If the npm package needs a build or transpiling step beforhand, this won't work.
You need a way to get the package build within the ember-cli build pipeline.
Luckily there are addons which can take care of this for you: ember-auto-import and ember-cli-cjs-transform.
You may have also heard of ember-browserify, which does the same thing, but it's deprectaed in favor of ember-auto-import.
I'd suggest you try ember-auto-import:
ember install ember-auto-import
You then should be able to import as you tried:
import { MDCTemporaryDrawer, MDCTemporaryDrawerFoundation, util } from '#material/drawer';
No shim or app.import needed, as ember-auto-import will take care of this for you.

How can I use a config file in React?

Let's say I have 5 jsx files and each file uses some config parameter.
My index.js file imports all of these 5 jsx files.
Instead of having my config data spread accross 5 files, is there a way for my jsx files to get the data from a global JS object which has loaded the data from a config file?
I've seen some examples, but I've not been able to get them to work.
JS6 import function | Example using webpack

Assuming ES6:
config.js
export const myConfig = { importantData: '', apiUrl: '', ... };
Then:
jsxFileOne.js, jsxFileTwo.js, ...
import { myConfig } from 'config.js';
There are other ways to import & export things globally leveraging webpack, but this should get you started.

If your project is built using Webpack, consider using node-env-file.
Example config file snippets:
development.env
API_SERVER_URL=https://www.your-server.com
webpack.config.js
const envFile = require('node-env-file');
...
const appSettingsFile = isDevBuild ? '/settings/development.env' : '/settings/production.env';
try {
envFile(path.join(__dirname + appSettingsFile));
} catch (error) {
console.log("Failed to read env file!: " + __dirname + appSettingsFile);
}
...
plugins: [
new webpack.DefinePlugin({
"process.env": {
API_SERVER_URL: JSON.stringify(process.env.API_SERVER_URL)
}
})
...
]
Inside your js/jsx code, you can now access process.env.API_SERVER_URL variable which will contain the required value.
It seems dotenv package is more popular, you can try this out as well.

Very old problem, that nobody took the time to solve, until now. I leave this for future readers because this is a top search result for configuration in React.
I created wj-config to deal exactly with this. Be sure to pay close attention to the React notes as you will need to enable top-level awaits in webpack, either by ejecting or using the #craco/craco NPM package.
You may also read this blog post that explains its use.