I support a relatively complex legacy codebase, but am looking to modernise it a little by bringing in Webpack so that we'd have import & export capabilities in JS.
The problem I'm having is that we use a global object called App where we define and add different properties depending on the page. So for example we have the following file where we instantiate App (loaded on all pages):
app.js
const App = (() => {
const obj = {
Lib: {},
Util: {},
// etc
}
return obj;
})();
Then in another file we add to App.Lib just for the specific page that needs it:
lazyload.js
App.Lib.Lazyload = (() => {
// lazyload logic
})();
We simply concatenate the files during the bundling process, but obviously this is not ideal as none of the files have no knowledge of what goes on outside of it.
Exporting only seems to work for the top level object (where the object is defined), so anything I add to it elsewhere cannot be exported again. For example if I add export default App.Lib.Lazyload; at the end of lazyload.js and then try to import it elsewhere it will not import the Lazyload property.
Is there any way to get this to work without major refactor? If not, would you have any suggestions about the best way to handle it?
I don't think you can import Object.properties in JS. If you want to bundle specific packages (say Lazyload) for packages that need them, you might try:
//lazyload.js
export const LazyLoad = {
//lazyload logic
}
then somewhere else...
import {LazyLoad} from 'path/to/lazyload.js';
// assuming App has already been created/instantiated
App.Lib.Lazyload = LazyLoad;
Using Export Default...
//lazyload.js
const LazyLoad = {};
export default LazyLoad;
then...
import LazyLoad from 'path/to/lazyload.js';
App.Lib.LazyLoad = LazyLoad;
You can find help with Imports and Exports at MDN.
import { keyFeatures } from 'common/data/AppClassic';
I am new to Next.js and using a template.
I have at least managed to succesfully add i18n, and I don't want to rebuild the whole template and the components... There is already a file in AppClassic that serves the content (pictures, text content ect). The easiest thing I thought of would be just duplicating this, and putting these files in different subpaths like 'en/common/data/AppClassic' or 'de/common/data/AppClassic' - And then somehow to import it with the dynamic locale const or conditionally render it, so if the locale const is 'en' then one file is imported, but if the const is 'de', then the other file is imported.
const router = useRouter();
const { locale } = router;
import { keyFeatures } from { locale } + '/common/data/AppClassic';
Is there a way to do something like that, and if so, could you provide some examples - since I have actually no Idea what I am doing.
I would be very grateful.
You could work your way with Next.js dynamic imports like the example:
import dynamic from 'next/dynamic'
const DynamicComponent = dynamic(() =>
import('../components/hello').then((mod) => mod.Hello)
)
For more info check their official docs:
https://nextjs.org/docs/advanced-features/dynamic-import
I have a project which has many files to export. For now I use CommonJS to lazy export those files:
module.exports = {
get AccessibilityInfo() {
return require('../Components/AccessibilityInfo/AccessibilityInfo');
},
get ActivityIndicator() {
return require('../Components/ActivityIndicator/ActivityIndicator');
},
// .... many other files
}
ReactNative do the same thing React Native, so that a file is only loaded when it is imported specifically.
I want to refactor this file with ESModule, but I can't find a way to export files lazily.
Is there a way to export files lazily with ESModule?
Is it necessary to export files lazily with ESModule?
The ECMAScript way of doing this is via dynamic import(). The syntax is basically the same and it does what you'd expect, except that it returns a promise (which is great - it means that the operation does not lock the thread). Your code could e.g. look like this:
export const getAccessibilityInfo = () =>
import("../Components/AccessibilityInfo/AccessibilityInfo");
export const getActivityIndicator = () =>
import("../Components/ActivityIndicator/ActivityIndicator");
You would then grab these modules like this:
import { getActivityIndicator } from "./the/module/above";
const ActivityIndicatorPromise = getActivityIndicator();
// Whenever you need to use the ActivityIdicator module, you first need to await for the promise resolution
ActivityIndicatorPromise.then(ActivityIndicatorModule => {
// Do what you want here...
});
You can read more about it here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/import#Dynamic_Imports. It also lists the cases where this syntax would be preferable. If you were hoping that this was possible using the static import syntax (import X from '../whatever';), rest assured - it is not.
No, there is not way to lazy export in react native
export does not have an effect on performance
import/require files have to make part of JS Bundle
components which are alive in memory put an effect on performance
In my point, there are three-way to make good performace
Solution 1: Dynamic Import
but you can load only dynamically component like this
const allPaths = {
path1: require('file path1').default,
path2: require('file path2').default
};
const MyComponent = allPaths('path1')
allPaths('path1') in this case only path1 component will be active
_
Solution 2: Stop render further Tree of Component
stop render on specific condition so further tree should not be active in memory and give not any effect on performace
render() {
const {isReady} = this.state;
if(!isReady)
{
return null;
}
return (
<ActualComponent />
)
}
-
Solution 3:Stop extra rerendering
you can use shouldComponentUpdate to stop extra renrendring. component on specifc condition only
shouldComponentUpdate(nextProps, nextState) {
return this.state.name != nextState.name;
}
Our Webpack bundle contains placeholders for the dynamic import of icons. An example dynamic import is as follows:
const { icon: iconName } = this.props;
const faIconName = `fa${iconName.replace(/./, c => c.toUpperCase())}`;
import(
/* webpackInclude: /\.js$/ */
`#fortawesome/pro-light-svg-icons/${faIconName}`
).then(faIcon => {
if (this.mounted) {
this.setState({ faIcon });
}
});
We decided for this strategy in order to prevent Webpack from bundling up the whole collection of FontAwesome icons.
Most recently we've realised the need to have internal builds where the dynamic import does not occur and pay the price of the larger bundle. The following code has been placed in our icon code (alongside the dynamic import above):
const faIconName = `fa${iconName.replace(/./, c => c.toUpperCase())}`;
let faIcon;
try {
faIcon = require(`#fortawesome/pro-light-svg-icons/${faIconName}.js`)[faIconName];
} catch (e) {}
Both loading strategies work fine when used one at a time. The issue comes when they coexist in the icon component.
I have verified that the import instruction leads Webpack to create in the bundle what to me seems a synthetic JS file generated with the command:
webpack:/// ./node_modules/#fortawesome/pro-light-svg-icons lazy ^\.\/.*$ include: \.js$ namespace object
When both import and require instructions are present in the Icon component, the synthetic file is different from when the sole import is encountered.
In detail, the object called map in the synthetic file contains values that are arrays with 3 elements in the import case and with 2 elements in the import+require case; the synthetic code tries to access the third element and everything crashes.
Can anyone comment on this issue?
I found an answer, you may check my full answer here
To make long story short i imported basing on the list and put all the imported components to Component's state. Afterwards i've created the React.createElememt's from the stored imported components and pulled all of them to Render
componentDidMount = () => {
//we get elements list from any source to redux-store
this.props.getForms();
//access redux-store to the list
const forms = this.props.configBody.sets;
//make deep object copy
const updatedState = { ...this.state };
updatedState.modules = [];
if (forms) {
//here is the very dynamic import magic: we map the import list and prepare to store the imports in Component`s state
const importPromises = forms.map(p =>
import(`../TemplateOrders/Template${p.order}`)
.then(module => {
updatedState.modules.push(module.default)
})
.catch(errorHandler(p))
)
//wait till all imports are getting resolved
Promise.all(importPromises)
.then(res =>
//then run setState
this.setState({ ...updatedState }, () => {
console.log(this.state);
}))
}
}
I am building an app with NodeJS and would like to use React for some of the interactive components across the application. I do not want to make it single page app.
How do I break up or bundle my React components across a multi-page app?
Currently all my components are in one file even though I may never load them in some sections of the app.
So far I am trying using conditional statements to render components by searching for the ID of the container where React will render. I am not 100% sure of what the best practices are with React. It looks something like this.
if(document.getElementById('a-compenent-in-page-1')) {
React.render(
<AnimalBox url="/api/birds" />,
document.getElementById('a-compenent-in-page-1')
);
}
if(document.getElementById('a-compenent-in-page-2')) {
React.render(
<AnimalBox url="/api/cats" />,
document.getElementById('a-compenent-in-page-2')
);
}
if(document.getElementById('a-compenent-in-page-3')) {
React.render(
<AnimalSearchBox url="/api/search/:term" />,
document.getElementById('a-compenent-in-page-3')
);
}
I am still reading the documentation and haven't found what I need yet for a multi page app.
Currently, I am doing something similar.
The application is not a full React App, I am using React for dynamic Stuff, like CommentBox, which is autark. And can be included at any Point with special params..
However, all my sub Apps are loaded and included into a single file all.js, so it can be cached by the browser across pages.
When I need to include an App into the SSR Templates, I just have to include a DIV with the class "__react-root" and a special ID, ( the name of the React App to be rendered )
The logic is really simple:
import CommentBox from './apps/CommentBox';
import OtherApp from './apps/OtherApp';
const APPS = {
CommentBox,
OtherApp
};
function renderAppInElement(el) {
var App = APPS[el.id];
if (!App) return;
// get props from elements data attribute, like the post_id
const props = Object.assign({}, el.dataset);
ReactDOM.render(<App {...props} />, el);
}
document
.querySelectorAll('.__react-root')
.forEach(renderAppInElement)
<div>Some Article</div>
<div id="CommentBox" data-post_id="10" class="__react-root"></div>
<script src="/all.js"></script>
Edit
Since webpack perfectly supports code-splitting & LazyLoading, I thought it make sense to include an example where you don't need to load all your apps in one bundle, but split them up and load on demand.
import React from 'react';
import ReactDOM from 'react-dom';
const apps = {
'One': () => import('./One'),
'Two': () => import('./Two'),
}
const renderAppInElement = (el) => {
if (apps[el.id]) {
apps[el.id]().then((App) => {
ReactDOM.render(<App {...el.dataset} />, el);
});
}
}
You can provide several entry points for the application in the webpack.config.js file:
var config = {
entry: {
home: path.resolve(__dirname, './src/main'),
page1: path.resolve(__dirname, './src/page1'),
page2: path.resolve(__dirname, './src/page2'),
vendors: ['react']
},
output: {
path: path.join(__dirname, 'js'),
filename: '[name].bundle.js',
chunkFilename: '[id].chunk.js'
},
}
then you can have in your src folder three different html files with their respective js files (example for page1):
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Page 1</title>
</head>
<body>
<div id="app"></div>
<script src="./vendors.js"></script>
<script src="./page1.bundle.js"></script>
</body>
</html>
JavaScript file:
import React from 'react'
import ReactDom from 'react-dom'
import App from './components/App'
import ComponentA from './components/ReactComponentA'
ReactDom.render(<div>
<App title='page1' />
<ReactComponentA/>
</div>, document.getElementById('app'))
Different React components can be then loaded for each single page.
I'm building an application from the ground up and am learning as I go, but I think what you are looking for is React-Router. React-Router maps your components to specific URLs. For example:
render((
<Router>
<Route path="/" component={App}>
<Route path="api/animals" component={Animals}>
<Route path="birds" component={Birds}/>
<Route path="cats" component={Cats}/>
</Route>
</Route>
<Route path="api/search:term" component={AnimalSearchBox}>
</Router>
), document.body)
In the search case, 'term' is accessible as a property in the AnimalSearchBox:
componentDidMount() {
// from the path `/api/search/:term`
const term = this.props.params.term
}
Try it out. This tutorial is the one that put me over the top in terms of my understanding of this and other related topics.
Original answer follows:
I found my way here looking for the same answer. See if this post inspires you. If your application is anything like mine, it will have areas that change very little and varies only in the main body. You could create a widget whose responsibility it is to render a different widget based upon the state of the application. Using a flux architecture, you could dispatch a navigation action that changes the state your body widget switches upon, effectively updating the body of the page only.
That's the approach I'm attempting now.
Are you using a CMS? They tend to like changing urls which could break your application.
Another way is using something like React Habitat.
With it, you can register components and they automatically get exposed to the dom.
Example
Register component(s):
container.register('AnimalBox', AnimalBox);
container.register('AnimalSearchBox', AnimalSearchBox);
Then they are availiable in your dom like this:
<div data-component="AnimalBox"></div>
<div data-component="AnimalSearchBox"></div>
The above will be automatically replaced with your react components.
You can then automatically pass properties (or props) to your components too:
<div data-component="AnimalBox" data-prop-size="small"></div>
This will expose size as a prop to your component. There are additional options for passing other types such as json, array's, ints, floats etc.
I know it's been a while since this question was asked but hopefully this helps someone.
As #Cocomico mentioned you could provide several entry points for the application in the webpack.config.js file. If you are looking for a simple Webpack setup (based on the idea of multiple entry points) that allows you to add React components to static pages you may consider using this: https://github.com/przemek-nowicki/multi-page-app-with-react
I revive this old question since I was in the same situation, without finding an answer that could satisfy my needs. So, based on #webdeb 's answer, I wrote a mini-framework that use CRA (without eject) to inject as many components you want in any HTML page while preserving all the CRA's benefits.
TL;DR
You can check my public repo here that contains all the needed files and a link to a Medium article where I thoroughly explain all this stuff.
The general idea
The trick is to install CRA as you normally would, and update the index.js file as follows :
import React, { Suspense } from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import reportWebVitals from './reportWebVitals';
//list here all the components that could be inserted in a web page
const apps = {
'App': React.lazy(() => import('./App')),
'TestComponent1': React.lazy(() => import('./TestComponent1')),
'TestComponent2': React.lazy(() => import('./TestComponent2')),
}
//event manager to communicate between the components
const bridgeEvent = new EventTarget();
//common fallback for all the components
function Fallback() {
return <div>Loading...</div>;
}
const renderAppInElement = (el) => {
if(apps[el.dataset.reactComponent] && !el.dataset.rendered){
//get the component's name stored in the data-react-component attribute
const App = apps[el.dataset.reactComponent];
//render the component, inject all the HTML attributes and the Event bridge
ReactDOM.render(
<Suspense fallback={<Fallback />}>
<App {...el.dataset} bridgeEvent={bridgeEvent}/>
</Suspense>
, el);
el.dataset.rendered = true;
}
else if(el.dataset.rendered){
console.log('el', el, 'is already rendered')
}
}
//ONLY FOR THE DEV PHASE
const rootEl = document.getElementById('root');
//generate components without attributes
if(process.env.REACT_APP_RENDER_CMP){
const components = process.env.REACT_APP_RENDER_CMP.split(',');
components.forEach(item => {
const componentEl = document.createElement('div');
componentEl.setAttribute("data-react-component", item);
componentEl.className = "__react-cmp";
rootEl.append(componentEl);
});
}
//generate components with attributes
if(process.env.REACT_APP_RENDER_CMP_WITH_ATTRS){
let componentsWithAttrs;
try{
componentsWithAttrs = JSON.parse(process.env.REACT_APP_RENDER_CMP_WITH_ATTRS);
}
catch(e){
console.log('fail to parse REACT_APP_RENDER_CMP_WITH_ATTRS', e);
}
if(componentsWithAttrs){
componentsWithAttrs.forEach(cmp => {
const componentEl = document.createElement('div');
componentEl.setAttribute("data-react-component", cmp.class);
componentEl.className = "__react-cmp";
Object.keys(cmp.data).forEach(attrKey => {
componentEl.setAttribute(attrKey, cmp.data[attrKey]);
});
rootEl.append(componentEl);
});
}
}
//the default name of the global object is ReactComponents, but it could be customized via the REACT_APP_NAMESPACE environment variable
const appNamespace = process.env.REACT_APP_NAMESPACE || "ReactComponents";
window[appNamespace] = {
ready: false,
parseComponents(container){
//parse the container or the whole document and inject all the components in the containers that have a "__react-cmp" class
(container || document)
.querySelectorAll('.__react-cmp')
.forEach(renderAppInElement);
}
}
window[appNamespace].parseComponents();
window[appNamespace].ready = true;
//if dynamic parsing must be done via the window.ReactComponents.parseComponents() method
//check the availability of window.ReactComponents object via window.ReactComponents.ready property
//or define a window.ReactComponentsAsyncInit() method to be notified of the availability
if(typeof window[`${appNamespace}AsyncInit`] === 'function'){
window[`${appNamespace}AsyncInit`]();
}
// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
reportWebVitals();
Then you can add REACT_APP_RENDER_CMP and/or REACT_APP_RENDER_CMP_WITH_ATTRS environment variables to test your components while using the CRA's development server. Your .env.development.local file could look like:
#this will render the TestComponent1 and TestComponent2 without any attributes
REACT_APP_RENDER_CMP="TestComponent1,TestComponent2"
#this will render TestComponent1 with the data-test-attribute attribute set to "test attribute value"
REACT_APP_RENDER_CMP_WITH_ATTRS="[{"class":"TestComponent1","data":{"data-test-attribute":"test attribute value"}}]"
After building your files, you should have your index.html file with all the .js and .css files you need to include in each page of your multi-page app that should load your React components. Don't forget to add INLINE_RUNTIME_CHUNK=false in your .env file to avoid any inline javascript!
Then, add the components' containers in the HTML pages where you want them to show. For instance:
<div class="__react-cmp" data-react-component="TestComponent1"></div>
The parseComponents() declared in the CRA's index.js file should be executed, grabbing your div with the .__react-cmp class, then use it as a container for your TestComponent1 React component.
In the dedicated repo and article I explain how you could change your build path with the CRA's BUILD_PATH environment variable (so you can host your built files in your server or in a CDN) and I provide a loader that will parse the built index.html file and dynamically insert all the needed .js and .css files in your page (so you just have to include the loader, instead of all the files). Here is how the loader looks like, assuming its file name is cmp-loader.js and hosted next to your built index.html file:
(async () => {
const head = document.getElementsByTagName('head')[0];
const scriptSrcRegexp = new RegExp('<script.*?src="(.*?)"', 'gmi');
//get the exact script's src as defined in the src attribute
const scriptSrc = scriptSrcRegexp.exec(document.currentScript.outerHTML);
//all the resources should be relative to the path of this script
const resourcesPath = (scriptSrc && scriptSrc.length > 1) ? scriptSrc[1].replace('cmp-loader.js', '') : '';
//get the index content
const indexHTML = await (await fetch(resourcesPath+'index.html', {cache:'reload'})).text();
//assume that all the .js and .css files to load are in the "static" folder
const reactCSSRegexp = new RegExp(`<link href="${resourcesPath}static\/css\/(.*?)\.css" rel="stylesheet">`, 'gm');
const reactJSRegexp = new RegExp(`<script (.*?) src="${resourcesPath}static\/js\/(.*?)\.js"><\/script>`, 'gm');
//grab all the css tags
const ReactCSS = [].concat(indexHTML.match(reactCSSRegexp)).join('');
//grab all the js tags
const ReactJS = [].concat(indexHTML.match(reactJSRegexp)).join('');
//parse and execute the scripts
const scriptsDoc = new DOMParser().parseFromString(ReactJS, 'text/html');
Array.from(scriptsDoc.getElementsByTagName('script')).forEach(item => {
const script = document.createElement('script');
[...item.attributes].forEach(attr => {
script.setAttribute(attr.name, attr.value)
})
head.appendChild(script);
});
//inject the CSS
head.insertAdjacentHTML('beforeend', ReactCSS);
})().catch(e => {
console.log('fail to load react-cmp', e)
});
I suggest you take a look at InertiaJS: https://inertiajs.com/
With Inertia you build apps just like you've always done with your server-side web framework of choice. You use your framework's existing functionality for routing, controllers, middleware, authentication, authorization, data fetching, and more.
The only thing that's different is your view layer. Instead of using server-side rendering (eg. Blade or ERB templates), the views are JavaScript page components. This allows you to build your entire front-end using React, Vue or Svelte.