I've been struggling with a very odd bug(?) with regards to importing an API module into a nested component in a Vue app.
This is the simplest I could reduce the issue down to.
https://codesandbox.io/s/rough-tree-fqj7o
Essentially, the DogsCreate component renders the CreateDogsModal, which is importing the dogs module from the API directory.
As you can see, the codesandbox errors out even on the base URL with the error Cannot read property 'default' of undefined. If running this code locally not on codesandbox, the base URL renders ok, but if you go to /dogs/create, the error then becomes Failed to resolve component: CreateDogsModal.
The things I've found that fix this are:
Commenting out the API import statement in CreateDogsModal (not an option for us, we need to be able to create and import API modules)
Commenting out the TopNav component in main.js (...also not an option for us)
Importing the TopNav component in App.vue with a relative import or #/components/TopNav.vue works fine, but strangely importing CreateDogsModal and CreateTemplate in DogsCreate.vue with a relative import or #/components/[component-name].vue does not. Also, the latter would be somewhat acceptable as a long-term solution, but I'd prefer the #/components shorthand and that still leaves the root cause undetermined.
I'm using the default vue-cli webpack configuration and have checked via vue inspect that the alias seems to be set properly.
I've been spinning my wheels for a week trying to figure this out and just...cannot. Does anyone have any ideas for what may be happening?
It seems like a race condition in Webpack, using parallel builds, but I'm honestly not sure. I can see CreateDogsModal being pulled in from two places, starting from main.js:
'main.js'
- import 'App.vue'
- import '#/components/index.js'
- import and export 'CreateDogsModal.vue'
- import 'router/index.js'
- import '#/views/Dogs/DogsCreate.vue'
- import '#/components/index.js'
- import and export 'CreateDogsModal.vue'
One workaround is to remove the race by making the CreateDogsModal an async component in DogsCreate:
// DogsCreate.vue
import { defineAsyncComponent } from "vue";
import { CreateTemplate } from "#/components";
export default {
name: "DogsCreate",
components: {
CreateTemplate,
CreateDogsModal: defineAsyncComponent(() => import("#/components/CreateDogsModal.vue")),
},
};
demo
Related
For example, the recommended way of importing in React Bootstrap is to go this way:
import Button from 'react-bootstrap/Button' instead of import { Button } from 'react-bootstrap';
The reason is "Doing so pulls in only the specific components that you use, which can significantly reduce the amount of code you end up sending to the client."
source: https://react-bootstrap.github.io/getting-started/introduction/
Same for React MUI components:
import Button from '#mui/material/Button';
source: https://mui.com/material-ui/getting-started/usage/
I want to implement something similar in my React components library, to limit the usage of code in the bundle, but I don't know how they implement this specific pattern. I have looked at their code base, but I don't quite understand.
Basically it is all about modules and module files and their organization. You can have a lot of.. lets call them folders, "compoments/*" for example. "components/button", "components/alert", "component/badge", and other things. All of them will have some index.js or .ts file that will export or declare and export all the functionality that needed in order to make this component work, 'react-bootstrap/Button' for example. Ideally all those subfolders or submodules are independend from each other, no references between them but probably each one will have 1 reference to 1 common/shared submodule like "components/common" which will contain some constants, for example, and no references to other files. At the top level of them you will have another index.js or .ts file that is referencing all of those components, so "components/index.js" will import and reexport all the nested components index files. So in order to import a Button, for example, you can either import "components/index.js" file with all the other imports this file is using, either only 1 single "components/button/index.js" file which is obviously much more easy to fetch. Just imagine a tree data structure, you import root of the tree (root index.js) - you get all the tree nodes. You import one specific Node (components/button/index.js) of the tree - just load all the childs (imports) of that node.
Sorry for a long read but asuming you mentioned webpack - there is a technique called tree-shaking which will cut off all the unused things.
Info about modules: https://www.w3schools.com/js/js_modules.asp
Info about Tree-Shaking: https://webpack.js.org/guides/tree-shaking/
It might not be as complicated as you think. Let's say you write the following library:
// your-library.js
const A = 22
const B = 33
export function getA () { return A }
export function getB () { return B }
export function APlusB () { return A + B }
// a lot of other stuff here
If some consumer of your library wants to make use of the APlusB function, they must do the following:
// their-website.js
import { APlusB } from 'your-library'
const C = APlusB()
However, depending on how the code is bundled, they may or may not wind up with the entire your-library file in their web bundle. Modern bundling tools like Webpack may provide tree shaking to eliminate dead code, but this should be considered an additional optimization that the API consumer can opt into rather than a core behavior of the import spec.
To make your library more flexible, you can split up independent functions or chunks of functionality into their own files while still providing a full bundle for users who prefer that option. For example:
// your-library/constants.js
export const A = 22
export const B = 33
// your-library/aplusb.js
import { A, B } from 'constants'
export default function APlusB () { return A + B }
// your-library/index.js
// instead of declaring everything in one file, export it from each module
export * from 'constants'
export { default as APlusB } from 'aplusb'
// more exports here
For distribution purposes you can package your library like so:
your-library
|__aplusb.js
|__constants.js
|__index.js
You mentioned react-bootstrap and you can see this exact pattern in their file structure:
https://github.com/react-bootstrap/react-bootstrap/tree/master/src
and you can see they aggregate and re-export modules in their index file here:
https://github.com/react-bootstrap/react-bootstrap/blob/master/src/index.tsx
Essentially, what you are asking is:
"How to export react components"
OR
"How are react components exported to be able to use it in a different react project ?"
Now coming to your actual question:
import Button from 'react-bootstrap/Button' instead of import { Button } from 'react-bootstrap';
The reason is 'Button' component is the default export of that file react-bootstrap/Button.tsx. So there is no need for destructuring a specific component.
If you export multiple components/ functions out of a file, only 1 of them can be a default export.
If you have only 1 export in a file you can make it the default export.
Consider the file project/elements.js
export default function Button(){
// Implementation of custom button component
}
export function Link(){
// Implementation of custom Link component
}
function Image(){
// Implementation of custom Image component
}
Notice that the Button component has 'default' as a keyword and the Link component doesn't.
The Image component can't even be imported and can only be used by other functions/components in the same file.
Now in project/index.js
import 'Button', {Link} from './elements.js'
As Button component is the default export its possible to import without destructuring and as Link component is a regular export, I have to destructure it for importing.
I am trying to make my jest tests (used for a VueJS SPA) work since I integrated Three.js in one of my components, but I'm having some trouble. Everything works when I run the app, but tests crash with the error:
/Users/Whomever/FE/node_modules/three/examples/jsm/controls/OrbitControls.js:1
({"Object.<anonymous>":function(module,exports,require,__dirname,__filename,global,jest){import {
^^^^^^
SyntaxError: Cannot use import statement outside a module
I know that the source of the error is from the OrbitControls, but I can't manage to get around this. I have tried to import /js instead of /jsm in my component, but then I get the error saying that "THREE is not defined". Also, the thing I least understand is the fact that this single component (which is four children layers deep from the App.vue file) crashes every test, even all the components that don't use Three.js at all.
I have also tried to set THREE globally in the main Vue definition, without success. Here is how my component file is coded:
import Vue from "vue";
import { OrbitControls } from "three/examples/jsm/controls/OrbitControls";
import * as THREE from "three";
export default Vue.extend({
name: "Some3DComponent",
components: {}
data: () => ({
displayModes: [],
viewWidth: 100,
viewHeight: 100,
modelClickableElements: null,
has3dModel: false,
ground: null,
animationFrame: null,
editorMode: null,
renderGround: true,
scales: null
}),
//Rest of the code that calls THREE and OrbitControls
});
Finally I have also tried to import THREE in the index.html file, no success. Now I'm running out of options.
The problems began only since using Three.js, all tests were functional before that.
Thanks in advance for the help!
You should not import OrbitControls from the examples folder. This is a custom function.
Try copy/paste the example code you need to a new TypeScript class into your project. Then you should be able to import it correctly. Beware they probably both import THREE so you might have context issues.
I've imported prism.js globally in main.js file.
Code block syntax highlighting working fine in Home components, but after routing to another page using vue-router, there is no effect.
in main.js
// Global Import
import 'prismjs/prism.js'
import 'prismjs/components/prism-swift.min.js' // swift lang
import './theme/prism-swift-theme.css'
in my about page component...
<pre><code class="language-swift">
private func setupSubviews() {
let value = "Loading code block";
}
</code></pre>
Unable to understand what's wrong here. Is there any way I can import node_modules prismjs files globally? I thought keeping main.js will work fine, but it's not adding globally between routes...
Once you install it with npm the best approach is to import it whenever it is used in each component seperately with import Prism from 'prismjs'. Just make sure to use the Prism.highlightAll() method in the component where you're using prism after the DOM is rendered whether in mount() hook or in the updated Vuejs hook using nextTick method to make sure all the DOM is rendered before using prism. So in your case you should use it this way:
import Prism from "prismjs"
updated: function () {
this.$nextTick(function () {
Prism.highlightAll();
})
}
make sure you call highlightAll in yor components seperately and not globaly.
I am very new to Vue and I have read an article or two about it (probably vaguely).
Also, Since I have some understanding of react, I tend to assume certain things to work the same way (but probably they do not)
Anyway, I just started with Quasar and was going through the Quasar boilerplate code
In the myLayout.vue file, I see being used inside my template
<template>
<q-layout view="lHh Lpr lFf">
<q-layout-header>
<q-toolbar
color="negative"
>
<q-btn
flat
dense
round
#click="leftDrawerOpen = !leftDrawerOpen"
aria-label="Menu"
>
<q-icon name="menu" />
</q-btn>
based on my vaguely understanding, I thought for every component we are using to whom we need to pass props we need to import it as well but unfortunately I can't see it in my import-script area
<script>
import { openURL } from 'quasar'
export default {
name: 'MyLayout',
data () {
return {
leftDrawerOpen: this.$q.platform.is.desktop
}
},
methods: {
openURL
}
}
</script>
I would've thought the script to be something like
<script>
import { openURL } from 'quasar'
import {q-icon} from "quasar"
or at least something like that but here we only have
import { openURL } from 'quasar'
Also, Even if we remove the above snippet, our boilerplate app looks to be working fine so here are my two questions
Question 1: What is the use of import { openURL } from 'quasar' (like what it does)
Question 2: How can template contain <quasar-icon> or <quasar-whatever> without even importing it in script tag?
How can template contain <quasar-icon> or <quasar-whatever> without even importing it in script tag?
There are two ways to import components. The first way (which I recommend, and being most similar to React) is to import the component and add it to the components option inside the component that you want to use it within.
App.vue
<div>
<my-component/>
</div>
import MyComponent from 'my-component'
export default {
components: {
MyComponent
}
}
The second way is to import it globally for use within any Vue component in your app. You need only do this once in the entry script of your app. This is what Quasar is doing.
main.js
import Vue from 'vue'
import MyComponent from 'my-component'
Vue.component('my-component', MyComponent)
What is the use of import { openURL } from 'quasar' (like what it does)
I'm not familiar with Quasar, so I can't give you a specific answer here (I don't know what openURL does). You should check the Quasar docs.
openURL is being used as a method here. Perhaps it is being called from somewhere in the template (which you have excluded from the question).
A1) Import statement is 1 way (es6) way to split your code into different files and then import functions/objects/vars from other files or npm modules see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import
A2) Vue allows 2 mechanisms to register components. Global and local. Globally registered components does not have to be imported and registered in every component before use (in template or render fn). See URL from comment above https://v2.vuejs.org/v2/guide/components-registration.html#Global-Registration
Currently a typical component will look like the below code. Note that using the paths to the file has become problematic and ugly. Moving a file causes massive issues with updating paths across multiple components.
This truly takes away from the component based experience when a path change can break everything and cause mass find and replace of paths.
In an ideal world the displayName would be the import reference and searched for within the directory.
'use strict';
//libs
import React from 'react';
//components
import TopFeatures from '../../headphones/subcomponents/top-features';
import Prices from './prices';
import Image from '../../layout/image';
import InlineRatingElement from '../../reviews/rating';
//helpers
import { getImageUrl } from '../../helpers/app/image';
import { initiateInlineRatings } from '../../helpers/app/inline-ratings';
export default class HDOverview extends React.Component {
displayName = 'HDOverview'
static propTypes = {
vendor: React.PropTypes.string.isRequired
}
constructor(props) {
super(props);
}
render() {
return (
<div>
JSX
</div>
);
}
}
I am looking to do something like this:
import TopFeatures from 'TopFeatures';//TopFeatures is the displayName
import Prices from 'Prices'; //Prices is the displayName etc.
import Image from 'Image';
import InlineRatingElement from 'InlineRatingElement';
//helpers
import { getImageUrl } from 'ImageHelper';
import { initiateInlineRatings } from 'InlineRatingHelper';
Webpack has a great tutorial on resolve aliases here: http://xabikos.com/javascript%20module%20bundler/javascript%20dependencies%20management/2015/10/03/webpack-aliases-and-relative-paths.html
However this insinuates that the path to the component would need to be logged in one place - in an ideal world there would be a way to dynamically check paths / directories to find the displayName that matches. Note that we have 200 components, so manually creating that list is do-able but sizable.
Having looked around I have seen people using
require("components!/layout/image")
however we would like to stick to the import technique and not go back to require.
Any suggestions or advice are greatly appreciated.
I think that this is, unfortunately, a limitation of node, npm.
There are workarounds to get absolute/mapped paths to work in npm but all of these have drawbacks: https://gist.github.com/branneman/8048520
Another option is individual npm packages for each component, but this adds a lot of overhead.