i have a question about multiple imports in React.
i have a structure like that eg:
src
validations
required
index.js
number
index.js
and i basically import these files to my React component with this way and everything works well
import {required} from "validations/required";
import {number} from "validations/number";
but when these imports is to much my file is getting so much line of code and looks ugly.
so i tried to make it like that:
import {required, number} from "validations";
and like that:
import {required, number} from "validations/";
booth solutions not worked.
It's giving to me error:
Module not found: Can't resolve 'validations/' in '/Users/...../Components/MyComponent'
i didn't understand why but seems like react search that files in my MyComponent folder.
how can handle it ?
Related
I'm trying to use code splitting in my react app and overall it works great, but I noticed something strange in bundle analyzer. My components folder is loaded in the first chunk with all its components (even the ones that are only used in lazy loaded components).
I think the problem is that I follow the structure of using index.ts files to export my components:
/components:
/Component1
/Child1
Child1.tsx
index.ts
Component1.tsx
index.ts
/Component2
Component2.tsx
index.ts
index.ts
The index.ts files just export the needed components like so
export * from './Component';
this is the same as
import { Component } from './Component';
export { Component };
in javascript.
By doing it that way I get very nice looking imports:
import { Component } from 'components';
without the deep paths and all that stuff.
But i think because of that webpack can not recognize how to split it and just bundles it all.
Are there any solutions for this? Maybe I'm doing something wrong?
I use the default create react app config right now.
export * from './Component';
This is causing webpack to bundle all the components which are there in './Component' and whatever it importing and so on.
You should export components individually without using *
Like export { Component1, Component2 } from './Component'
Also if you are using Webpack 5, it creates a mapping of which component import is used and discard unused components. This is not available in Webpack 4.
I have read somewhere that importing module in react with curly braces around imports the entire library instead and effectively increases the bundle size. I was using this concept and was successfull in importing modules without curly braces, like this:
import Jumbotron from 'reactstrap';
and it was working fine. I don't know why the next time I build the code, it started showing me this warning:
WARNING in ./React Coursera/Header.js 5:71-77
export default (imported as Jumbotron) was not found in reactstrap.
Also the app didn't run in browser.
Then I went to node_modules to check if export default is present in jumbotron or not, and I found this statement:
export default Jumbotron;
It means that indeed it was exporting the Jumbotron as default, then why it showed me this warning.
Can you help me guys to fix this problem?
Thanks in advance!
Where did you read that importing with curly will increase the bundle size, it's reverse,
// below line will import everything
import * as reactstrap from 'reactstrap'
But
// this will import only specific module
import { Jumbotron } from 'reactstrap'
By this line :
// will import from /reactstrap/index.js
import Jumbotron from 'reactstrap';
You are importing nothing https://github.com/reactstrap/reactstrap/blob/master/src/index.js , as there is export default
So I don't know how it worked before in your case
Below line :
// and this line is not inside the /reactstrap/index.js but /reactstrap/Jumbotron.js
export default Jumbotron;
is here : https://github.com/reactstrap/reactstrap/blob/master/src/Jumbotron.js
So you can do :
import { Jumbotron } from 'reactstrap'
It depends on your build setup and/or how the library code is setup. Some libraries are built in a way that won't import the entire library when you use curly braces. You can also have something enabled in your build tools called "tree shaking" which will remove all code that is unused.
I'm guessing what you were trying to do was import Jumbotron individually which is a safe bet when you are unsure if the whole lib will be imported. Again, it depends on the file structure of the library but you are probably missing the sub-directory in your import. There should be directories inside of the node_module folder for each component. Might be something like node_modules/reactstrap/Jumbotron. The default export you saw was probably on the Jumbotron file. When you use import Jumbotron from 'reactstrap' you are asking it do find a default export for the "main" file of the library. This would be defined in the package.json file of the library.
What you need to do is add the sub-directory to your import like so (just guessing here) import Jumbotron from 'reactstrap/Jumbotron'. Just think of reactstrap/ being the root directory of the library, you can select any file like you normally would.
If you are using webpack, there's this awesome plugin where you can check to see what is included in your bundles just to make sure you are indeed only importing the code that you need https://github.com/webpack-contrib/webpack-bundle-analyzer
Let's say I have multiple javascript files, along with several node modules, and in each file I do something like this:
import 'node_module_a'
import 'node_module_b'
import 'node_module_c'
I find myself repeating this same code across all my javascript files, so I'm wondering is there a compact way (like bundling) to add all this to a single file, and just import from that?
Like:
in all_the_things.js:
import 'node_module_a'
import 'node_module_b'
import 'node_module_c'
Then add only this line in all javascript files:
import * from 'all_the_things.js'
I tried reading some documentation to give me ideas, but I'm at a loss here.
I had no idea I literally wrote the answer in the question. I tried all kinds of stuff, except what I posted. When I tried it, it worked.
If you put
in all_the_things.js:
import 'node_module_a'
import 'node_module_b'
import 'node_module_c'
then you do this in the caller js file:
import 'all_the_things'
it will import all the nodes. Also, I found out if you put those imports in a parent file, loading only once, it will be viewed by other child components.
I am trying to import an external JavaScript library with no typings or installable package. The plugin is: https://github.com/amw/jpeg_camera/tree/master/dist/jpeg_camera_no_flash.js. I want to import three classes from that plugin: JpegCamera, JpegCameraHTML5 and Snapshot. With the help of some tutorials, I was able to export the three classes with their interfaces in a .d.ts file. The .d.ts file looks something like:.
declare module Camera {}
export class JpegCamera {...}
export class JpegCameraHTML5 {...}
export class Snapshot {...}
Now, I don't know how to create a link between the plugin source file (.js), my own .d.ts file and the typescript file where I want to import these three classes. I tried
import * as X from "path/to/d.ts
but it won't work. Thanks :)
I don't know in which context you are running your application, but trying locally I got the message: ReferenceError: document is not defined loading with the syntax:
import * as camera from './jpeg_camera_no_flash'
You should not have this message if you are running your script through a browser.
I downloaded the file physically to my project folder.
You could try doing this:
/// <reference path="path to the .d.ts" />
Or you could export each class using default, so you can import them like this: import className from './file-path'
I’m running my react app via Node. Is there a way to easily handle this import hell?
I’m running
./node_modules/.bin/babel-node --presets react,es2015 server/server.js
as npm start. And server.js is a simple Express Server that serves a ReactDOMServer.renderToString(<MyApp />)
Some of my react components have something like this:
import GenericTemplate from "../../templates/GenericTemplate/GenericTemplate";
import Footer from "../../organisms/Footer/Footer";
import Header from "../../organisms/Header/Header";
import Hero from "../../organisms/Hero/Hero";
import MainMenu from "../../organisms/MainMenu/MainMenu";
import TodoList from "../../organisms/TodoList/TodoList";
this is prone to error, one changement like directory name would result in manually entering every file to update this.
do you have any idea how I can fix this. Ideally I would have something like this:
import { Footer, Header, Hero, MainMenu, TodoList } from "myComponents"
is that possible? How?
Thank you!
This also doesn't look a lot better to me:
import { Footer, Header, Hero, MainMenu, TodoList } from "myComponents"
... because in order to do that, you need to export / import to "myComponents" every time you create a new component.
The core issue I see in your example is that using relative paths for imports makes your code base very hard to maintain.
To escape the "import hell" in React, one popular option is to make the import statements without relative paths.
With a minor tweak to your Webpack configuration, you can get it to load files relative to the app root. See here and read more here.
You can create a common components file in your organisms directory to achieve that. Just create a new common.js or whatever name with the following:
export Footer from "./Footer/Footer";
export Header from "./Header/Header";
export Hero from "./Hero/Hero";
export MainMenu from "./MainMenu/MainMenu";
export TodoList from "./TodoList/TodoList";
Then in your other file:
import { Footer, Header, Hero, MainMenu, TodoList } from "path to common.js"