React Hot Loader: Tweak React Components in Real Time.

React Hot Loader

Tweak React components in real time ⚛️⚡️

Watch Dan Abramov's talk on Hot Reloading with Time Travel.

Moving towards next step

React-Hot-Loader has been your friendly neighbour, living outside of React. But it has been limiting its powers and causing not the greatest experience. It's time to make a next step.

React-Hot-Loader is expected to be replaced by React Fast Refresh. Please remove React-Hot-Loader if Fast Refresh is currently supported on your environment.

React Native - supports Fast Refresh since 0.61.
parcel 2 - supports Fast Refresh since alpha 3.
webpack - supports Fast Refresh using a plugin.
other bundler - no support yet, use React-Hot-Loader
create-react-app - supports Fast Refresh with FAST_REFRESH env since 4.
next.js - supports Fast Refresh since 9.4

Install

npm install react-hot-loader

Note: You can safely install react-hot-loader as a regular dependency instead of a dev dependency as it automatically ensures it is not executed in production and the footprint is minimal.

Getting started

Add react-hot-loader/babel to your .babelrc:

// .babelrc
{
  "plugins": ["react-hot-loader/babel"]
}

Mark your root component as hot-exported:

// App.js
import { hot } from 'react-hot-loader/root';
const App = () => <div>Hello World!</div>;
export default hot(App);

Make sure react-hot-loader is required before react and react-dom:

or import 'react-hot-loader' in your main file (before React)
or prepend your webpack entry point with react-hot-loader/patch, for example:

// webpack.config.js
module.exports = {
  entry: ['react-hot-loader/patch', './src'],
  // ...
};

If you need hooks support, use @hot-loader/react-dom

Hook support

Hooks would be auto updated on HMR if they should be. There is only one condition for it - a non zero dependencies list.

❄️ useState(initialState); // will never updated (preserve state)
❄️ useEffect(effect); // no need to update, updated on every render
❄️ useEffect(effect, []); // "on mount" hook. "Not changing the past"
🔥 useEffect(effect, [anyDep]); // would be updated

🔥 useEffect(effect, ["hot"]); // the simplest way to make hook reloadable

Plus

any hook would be reloaded on a function body change. Enabled by default, controlled by reloadHooksOnBodyChange option.
you may configure RHL to reload any hook by setting reloadLifeCycleHooks option to true.

To disable hooks reloading - set configuration option:

import { setConfig } from 'react-hot-loader';

setConfig({
  reloadHooks: false,
});

With this option set all useEffects, useCallbacks and useMemo would be updated on Hot Module Replacement.

Hooks reset

Hooks would be reset if their order changes. Adding, removing or moving around would cause a local tree remount.

Babel plugin is required for this operation. Without it changing hook order would throw an error which would be propagated till the nearest class-based component.

`@hot-loader/react-dom`

@hot-loader/react-dom replaces the "react-dom" package of the same version, but with additional patches to support hot reloading.

There are 2 ways to install it:

Use yarn name resolution, so @hot-loader/react-dom would be installed instead of react-dom

yarn add react-dom@npm:@hot-loader/react-dom

Use webpack aliases

yarn add @hot-loader/react-dom

// webpack.config.js
module.exports = {
  // ...
  resolve: {
    alias: {
      'react-dom': '@hot-loader/react-dom',
    },
  },
};

Old API

Note: There is also an old version of hot, used prior to version 4.5.4. Please use the new one, as it is much more resilient to js errors that you may make during development.

Meanwhile, not all the bundlers are compatible with new /root API, for example parcel is not.

React-Hot-Load will throw an error, asking you to use the old API, if such incompatibility would be detected. It is almost the same, but you have to pass module inside hot.

import { hot } from 'react-hot-loader';
const App = () => <div>Hello World!</div>;
export default hot(module)(App);

Run webpack with Hot Module Replacement:

webpack-dev-server --hot

What about production?

The webpack patch, hot, Babel plugin, @hot-loader/react-dom etc. are all safe to use in production; they leave a minimal footprint, so there is no need to complicate your configuration based on the environment. Using the Babel plugin in production is even recommended because it switches to cleanup mode.

Just ensure that the production mode has been properly set, both as an environment variable and in your bundler. E.g. with webpack you would build your code by running something like:

NODE_ENV=production webpack --mode production

NODE_ENV=production is needed for the Babel plugin, while --mode production uses webpack.DefinePlugin to set process.env.NODE_ENV inside the compiled code itself, which is used by hot and @hot-loader/react-dom.

Make sure to watch your bundle size when implementing react-hot-loader to ensure that you did it correctly.

Limitations

(that's the goal) React-Hot-Loader would not change the past, only update the present - no lifecycle event would be called on component update. As a result, any code changes made to componentWillUnmount or componentDidMount would be ignored for already created components.
(that's the goal) React-Hot-Loader would not update any object, including component state.
(1%) React-Hot-Loader may not apply some changes made to a component's constructor. Unless an existing component is recreated, RHL would typically inject new data into that component, but there is no way to detect the actual change or the way it was applied, especially if the change was made to a function. This is because of the way React-Hot-Loader works - it knows what class functions are, not how they were created. See #1001 for details.

Recipes

Migrating from create-react-app

Run npm run eject
Install React Hot Loader (npm install --save-dev react-hot-loader)
In config/webpack.config.dev.js, add 'react-hot-loader/babel' to Babel loader configuration. The loader should now look like:

  {
    test: /\.(js|jsx)$/,
    include: paths.appSrc,
    loader: require.resolve('babel-loader'),
    options: {
      // This is a feature of `babel-loader` for webpack (not Babel itself).
      // It enables caching results in ./node_modules/.cache/babel-loader/
      // directory for faster rebuilds.
      cacheDirectory: true,
      plugins: ['react-hot-loader/babel'],
    },
  }

Mark your App (src/App.js) as hot-exported:

// ./containers/App.js
import React from 'react';
import { hot } from 'react-hot-loader';

const App = () => <div>Hello World!</div>;

export default hot(module)(App);

Migrating from create-react-app without ejecting

Users report, that it is possible to use react-app-rewire-hot-loader to setup React-hot-loader without ejecting.

TypeScript

As of version 4, React Hot Loader requires you to pass your code through Babel to transform it so that it can be hot-reloaded. This can be a pain point for TypeScript users, who usually do not need to integrate Babel as part of their build process.

Fortunately, it's simpler than it may seem! Babel will happily parse TypeScript syntax and can act as an alternative to the TypeScript compiler, so you can safely replace ts-loader or awesome-typescript-loader in your Webpack configuration with babel-loader. Babel won't typecheck your code, but you can use fork-ts-checker-webpack-plugin (and/or invoke tsc --noEmit) as part of your build process instead.

A sample configuration:

{
  // ...you'll probably need to configure the usual Webpack fields like "mode" and "entry", too.
  resolve: { extensions: [".ts", ".tsx", ".js", ".jsx"] },
  module: {
    rules: [
      {
        test: /\.(j|t)sx?$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader",
          options: {
            cacheDirectory: true,
            babelrc: false,
            presets: [
              [
                "@babel/preset-env",
                { targets: { browsers: "last 2 versions" } } // or whatever your project requires
              ],
              "@babel/preset-typescript",
              "@babel/preset-react"
            ],
            plugins: [
              // plugin-proposal-decorators is only needed if you're using experimental decorators in TypeScript
              ["@babel/plugin-proposal-decorators", { legacy: true }],
              ["@babel/plugin-proposal-class-properties", { loose: true }],
              "react-hot-loader/babel"
            ]
          }
        }
      }
    ]
  },
  plugins: [
    new ForkTsCheckerWebpackPlugin()
  ]
};

For a full example configuration of TypeScript with React Hot Loader and newest beta version of Babel, check here.

As an alternative to this approach, it's possible to chain Webpack loaders so that your code passes through Babel and then TypeScript (or TypeScript and then Babel), but this approach is not recommended as it is more complex and may be significantly less performant. Read more discussion here.

Parcel

Parcel supports Hot Module Reloading out of the box, just follow step 1 and 2 of Getting Started.

We also have a full example running Parcel + React Hot Loader.

Electron

You need something to mark your modules as hot in order to use React Hot Loader.

One way of doing this with Electron is to simply use webpack like any web-based project might do and the general guide above describes. See also this example Electron app.

A webpack-less way of doing it to use electron-compile (which is also used by electron-forge) - see this example. While it requires less configuration, something to keep in mind is that electron-compile's HMR will always reload all modules, regardless of what was actually edited.

Source Maps

If you use devtool: 'source-map' (or its equivalent), source maps will be emitted to hide hot reloading code.

Source maps slow down your project. Use devtool: 'eval' for best build performance.

Hot reloading code is just one line in the beginning and one line at the end of each module so you might not need source maps at all.

Linking

If you are using npm link or yarn link for development purposes, there is a chance you will get error Module not found: Error: Cannot resolve module 'react-hot-loader' or the linked package is not hot reloaded.

There are 2 ways to fix Module not found:

Use include in loader configuration to only opt-in your app's files to processing.
Alternatively if you are using webpack, override the module resolution in your config:

{
  resolve: {
    alias: {
      'react-hot-loader': path.resolve(path.join(__dirname, './node_modules/react-hot-loader')),
    }
  }
}

And to make your linked package to be hot reloaded, it will need to use the patched version of react and react-dom, if you're using webpack, add this options to the alias config

{
  resolve: {
    alias: {
      'react-hot-loader': path.resolve(path.join(__dirname, './node_modules/react-hot-loader')),
      // add these 2 lines below so linked package will reference the patched version of `react` and `react-dom`
      'react': path.resolve(path.join(__dirname, './node_modules/react')),
      'react-dom': path.resolve(path.join(__dirname, './node_modules/react-dom')),
      // or point react-dom above to './node_modules/@hot-loader/react-dom' if you are using it
    }
  }
}

Preact

React-hot-loader should work out of the box with preact-compat, but, in case of pure preact, you will need to configure it:

create configuration file (setupHotLoader.js)

import reactHotLoader from 'react-hot-loader';
import preact from 'preact';

reactHotLoader.preact(preact);

dont forget to import it

Preact limitations

HOCs and Decorators as not supported yet. For Preact React-Hot-Loader v4 behave as v3.

React Native

React Native supports hot reloading natively as of version 0.22.

Using React Hot Loader with React Native can cause unexpected issues (see #824) and is not recommended.

Webpack plugin

We recommend using the babel plugin, but there are some situations where you are unable to. If so, try the webpack plugin / webpack-loader (as seen in v3).

Remember - the webpack plugin is not compatible with class-based components. The babel plugin will inject special methods to every class, to make class members (like onClick) hot-updatable, while the webpack plugin would leave classes as is, without any instrumentation.

class MyComponent extends React.Component {
  onClick = () => this.setState(); // COULD NOT UPDATE
  variable = 1; // this is ok
  render() {} // this is ok
}

But webpack-loader could help with TypeScript or spreading "cold API" to all node_modules.

It is possible to enable this loader for all the files, but if you use babel plugin, you need to enable this loader for react-dom only. Place it after babel-loader, if babel-loader is present.

// webpack.config.js
module.exports = {
  module: {
    rules: [
      // would only land a "hot-patch" to react-dom
      {
        test: /\.js$/,
        include: /node_modules\/react-dom/,
        use: ['react-hot-loader/webpack'],
      },
    ],
  },
};

Webpack plugin will also land a "hot" patch to react-dom, making React-Hot-Loader more compliant to the principles.

If you are not using babel plugin you might need to apply webpack-loader to all the files.

{
  test: /\.jsx?$/,
  include: /node_modules/,
  use: ['react-hot-loader/webpack']
},

Code Splitting

If you want to use Code Splitting + React Hot Loader, the simplest solution is to pick a library compatible with this one:

If you use a not-yet-friendly library, like react-async-component, or are having problems with hot reloading failing to reload code-split components, you can manually mark the components below the code-split boundaries.

// AsyncHello.js
import { asyncComponent } from 'react-async-component';

// asyncComponent could not `hot-reload` itself.
const AsyncHello = asyncComponent({
  resolve: () => import('./Hello'),
});

export default AsyncHello;

Note that Hello is the component at the root of this particular code-split chunk.

// Hello.js
import { hot } from 'react-hot-loader/root';

const Hello = () => 'Hello';

export default hot(Hello); // <-- module will reload itself

Wrapping this root component with hot() will ensure that it is hot reloaded correctly.

Out-of-bound warning

You may see the following warning when code-split components are updated:

React-Hot-Loader: some components were updated out-of-bound. Updating your app to reconcile the changes.

This is because the hot reloading of code-split components happens asynchronously. If you had an App.js that implemented the AsyncHello component above and you modified AsyncHello, it would be bundled and reloaded at the same time as App.js. However, the core hot reloading logic is synchronous, meaning that it's possible for the hot reload to run before the updates to the split component have landed.

In this case, RHL uses a special tail update detection logic, where it notes that an an update to a split component has happened after the core hot reloading logic has already finished, and it triggers another update cycle to ensure that all changes are applied.

The warning is informational - it is a notice that this tail update logic is triggered, and does not indicate a problem in the configuration or useage of react-hot-loader.

If the tail update detection is not something you want or need, you can disable this behavior by setting setConfig({ trackTailUpdates:false }).

Checking Element `type`s

Because React Hot Loader creates proxied versions of your components, comparing reference types of elements won't work:

const element = <Component />;
console.log(element.type === Component); // false

React Hot Loader exposes a function areComponentsEqual to make it possible:

import { areComponentsEqual } from 'react-hot-loader';
const element = <Component />;
areComponentsEqual(element.type, Component); // true

Another way - compare "rendered" element type

const element = <Component />;
console.log(element.type === <Component />.type); // true

// better - precache rendered type
const element = <Component />;
const ComponentType = <Component />.type;
console.log(element.type === ComponentType); // true

But you might have to provide all required props. See original issue. This is most reliable way to compare components, but it will not work with required props.

Another way - compare Component name.

Not all components have a name. In production displayName could not exists.

const element = <Component />;
console.log(element.displayName === 'Component'); // true

This is something we did not solve yet. Cold API could help keep original types.

Webpack ExtractTextPlugin

webpack ExtractTextPlugin is not compatible with React Hot Loader. Please disable it in development:

new ExtractTextPlugin({
  filename: 'styles/[name].[contenthash].css',
  disable: NODE_ENV !== 'production',
});

Disabling a type change (❄️)

It is possible to disable React-Hot-Loader for a specific component, especially to enable common way to type comparison. See #991 for the idea behind ⛄️, and #304 about "type comparison" problem.

import { cold } from 'react-hot-loader';

cold(SomeComponent) // this component will ignored by React-Hot-Loader
<SomeComponent />.type === SomeComponent // true

If you will update cold component React-Hot-Loader will complain (on error level), and then React will cold-replace Component with a internal state lose.

Reach-Hot-Loader: cold element got updated

Disabling a type change for all node_modules

You may cold all components from node_modules. This will not work for HOC(like Redux) or dynamically created Components, but might help in most of situations, when type changes are not welcomed, and modules are not expected to change.

import { setConfig, cold } from 'react-hot-loader';
setConfig({
  onComponentRegister: (type, name, file) => file.indexOf('node_modules') > 0 && cold(type),

  // some components are not visible as top level variables,
  // thus its not known where they were created
  onComponentCreate: (type, name) => name.indexOf('styled') > 0 && cold(type),
});

! To be able to "cold" components from 'node_modules' you have to apply babel to node_modules, while this folder is usually excluded. You may add one more babel-loader, with only one React-Hot-Loader plugin inside to solve this. Consider using webpack-loader for this.

React-Hooks

React hooks are not really supported by React-Hot-Loader. Mostly due to our internal processes of re-rendering React Tree, which is required to reconcile an updated application before React will try to rerender it, and fail to do that, obviously.

hooks should work for versions 4.6.0 and above (pureSFC is enabled by default).
hooks will produce errors on every hot-update without patches to react-dom.
hooks may loss the state without patches to react-dom.
hooks does not support adding new hooks on the fly
change in hooks for a mounted components will cause a runtime exception, and a retry button (at the nearest class component) will be shown. Pressing a retry button will basically remount tree branch.

To mitigate any hook-related issues (and disable their hot-reloadability) - cold them.

cold components using hooks.

import { setConfig, cold } from 'react-hot-loader';
setConfig({
  onComponentCreate: (type, name) =>
    (String(type).indexOf('useState') > 0 || String(type).indexOf('useEffect') > 0) && cold(type),
});

API

`hot(Component, options)`

Mark a component as hot.

Babel plugin

Right now babel plugin has only one option, enabled by default.

safetyNet - will help you properly setup ReactHotLoader.

You may disable it to get more control on the module execution order.

//.babelrc
{
    "plugins": [
        [
            "react-hot-loader/babel",
            {
            "safetyNet": false
            }
        ]
    ]
}

Important

!! Use hot only for module exports, not for module imports. !!

import { hot } from 'react-hot-loader/root';

const App = () => 'Hello World!';

export default hot(App);

Keep in mind - by importing react-hot-loader/root you are setting up a boundary for update event propagation.

The higher(in module hierarchy) you have it - the more stuff would be updated on Hot Module Replacement.

To make RHL more reliable and safe, please place hot below (ie somewhere in imported modules):

react-dom
redux store creation
any data, you want to preserve between updates
big libraries

You may(but it's not required) place hot to the every route/page/feature/lazy chunk, thus make updates more scoped.

You don't need to wrap every component with hot, application work work fine with a single one.

(old)`hot(module, options)(Component, options)`

Mark a component as hot. The "new" hot is just hidding the first part - hot(module), giving you only the second (App). The "new" hot is using old API.

import { hot } from 'react-hot-loader';

const App = () => 'Hello World!';

export default hot(module)(App);

`AppContainer`

Mark application as hot reloadable. (Prefer using hot helper, see below for migration details).

This low-level approach lets you make **hot **imports__, not exports.

import React from 'react';
import ReactDOM from 'react-dom';
import { AppContainer } from 'react-hot-loader';
import App from './containers/App';

const render = Component => {
  ReactDOM.render(
    <AppContainer>
      <Component />
    </AppContainer>,
    document.getElementById('root'),
  );
};

render(App);

// webpack Hot Module Replacement API
if (module.hot) {
  // keep in mind - here you are configuring HMR to accept CHILDREN MODULE
  // while `hot` would configure HMR for the CURRENT module
  module.hot.accept('./containers/App', () => {
    // if you are using harmony modules ({modules:false})
    render(App);
    // in all other cases - re-require App manually
    render(require('./containers/App'));
  });
}

areComponentsEqual(Component1, Component2)

Test if two components have the same type.

import { areComponentsEqual } from 'react-hot-loader';
import Component1 from './Component1';
import Component2 from './Component2';

areComponentsEqual(Component1, Component2); // true or false

setConfig(config)

Set a new configuration for React Hot Loader.

Available options are:

logLevel: specify log level, default to "error", available values are: ['debug', 'log', 'warn', 'error']
pureSFC: enable Stateless Functional Component. If disabled they will be converted to React Components. Default value: false.
ignoreSFC: skip "patch" for SFC. "Hot loading" could still work, with webpack-patch present
pureRender: do not amend render method of any component.
for the rest see index.d.ts.

// rhlConfig.js
import { setConfig } from 'react-hot-loader';

setConfig({ logLevel: 'debug' });

It is important to set configuration before any other action will take a place

// index.js
import './rhlConfig' // <-- extract configuration to a separate file, and import it in the beggining
import React from 'react'
....

Migrating from v3

AppContainer vs hot

Prior v4 the right way to setup React Hot Loader was to wrap your Application with AppContainer, set setup module acceptance by yourself. This approach is still valid but only for advanced use cases, prefer using hot helper.

React Hot Loader v3:

// App.js
import React from 'react';

const App = () => <div>Hello world!</div>;

export default App;

// main.js
import React from 'react';
import ReactDOM from 'react-dom';
import { AppContainer } from 'react-hot-loader';
import App from './containers/App';

const render = Component => {
  ReactDOM.render(
    <AppContainer>
      <Component />
    </AppContainer>,
    document.getElementById('root'),
  );
};

render(App);

// webpack Hot Module Replacement API
if (module.hot) {
  module.hot.accept('./containers/App', () => {
    // if you are using harmony modules ({modules:false})
    render(App);
    // in all other cases - re-require App manually
    render(require('./containers/App'));
  });
}

React Hot Loader v4:

// App.js
import React from 'react';
import { hot } from 'react-hot-loader';

const App = () => <div>Hello world!</div>;

export default hot(module)(App);

// main.js
import React from 'react';
import ReactDOM from 'react-dom';
import App from './containers/App';

ReactDOM.render(<App />, document.getElementById('root'));

Patch is optional

Since 4.0 till 4.8

Code is automatically patched, you can safely remove react-hot-loader/patch from your webpack config, if react-hot-loader is required before React in any other way.

Error Boundary is inside every component

Since 4.5.4

On Hot Module Update we will inject componentDidCatch and a special render to every Class-based component you have, making Error Boundaries more local.

After update we will remove all sugar, keeping only Boundaries you've created.

You can provide your own errorReporter, via setConfig({errorReporter}) or opt-out from root ErrorBoundaries setting errorBoundary={false} prop on AppContainer or hot. However - this option affects only SFC behavior, and any ClassComponent would boundary itself.

import { setConfig } from 'react-hot-loader';
import ErrorBoundary from './ErrorBoundary';

// ErrorBoundary will be given error and errorInfo prop.
setConfig({ errorReporter: ErrorBoundary });

If errorReporter is not set - full screen error overlay would be shown.

Setting global Error Reporter

Global Error Reporter would, created a fixed overlay on top the page, would be used to display errors, not handled by errorReporter, and any HMR error.

You may change, or disable this global error overlay

// to disable
setConfig({ ErrorOverlay: () => null });

// to change
setConfig({ ErrorOverlay: MyErrorOverlay });

The UX of existing overlay is a subject to change, and we are open to any proposals.

Known limitations and side effects

Note about `hot`

hot accepts only React Component (Stateful or Stateless), resulting the HotExported variant of it. The hot function will setup current module to self-accept itself on reload, and will ignore all the changes, made for non-React components. You may mark as many modules as you want. But HotExportedComponent should be the only used export of a hot-module.

Note: Please note how often we have used exported keyword. hot is for exports.

Note: Does nothing in production mode, just passes App through.

New Components keep executing the old code

There is no way to hot-update constructor code, as result even new components will be born as the first ones, and then grow into the last ones. As of today, this issue cannot be solved.

Troubleshooting

If it doesn't work, in 99% of cases it's a configuration issue. A missing option, a wrong path or port. webpack is very strict about configuration, and the best way to find out what's wrong is to compare your project to an already working setup, check out examples, bit by bit.

If something doesn't work, in 99% of cases it's an issue with your code. The Component didn't get registered, due to HOC or Decorator around it, which is making it invisible to the Babel plugin or webpack loader.

We're also gathering Troubleshooting Recipes so send a PR if you have a lesson to share!

Switch into debug mode

Debug mode adds additional warnings and can tells you why React Hot Loader is not working properly in your application.

import { setConfig } from 'react-hot-loader';
setConfig({ logLevel: 'debug' });

Author: gaearon
Source Code: https://github.com/gaearon/react-hot-loader
License: MIT license

#react-native #react

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React Hot Loader: Tweak React Components in Real Time.

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How native is React Native? | React Native vs Native App Development

If you are undertaking a mobile app development for your start-up or enterprise, you are likely wondering whether to use React Native. As a popular development framework, React Native helps you to develop near-native mobile apps. However, you are probably also wondering how close you can get to a native app by using React Native. How native is React Native?

In the article, we discuss the similarities between native mobile development and development using React Native. We also touch upon where they differ and how to bridge the gaps. Read on.

A brief introduction to React Native

Let’s briefly set the context first. We will briefly touch upon what React Native is and how it differs from earlier hybrid frameworks.

React Native is a popular JavaScript framework that Facebook has created. You can use this open-source framework to code natively rendering Android and iOS mobile apps. You can use it to develop web apps too.

Facebook has developed React Native based on React, its JavaScript library. The first release of React Native came in March 2015. At the time of writing this article, the latest stable release of React Native is 0.62.0, and it was released in March 2020.

Although relatively new, React Native has acquired a high degree of popularity. The “Stack Overflow Developer Survey 2019” report identifies it as the 8th most loved framework. Facebook, Walmart, and Bloomberg are some of the top companies that use React Native.

The popularity of React Native comes from its advantages. Some of its advantages are as follows:

Performance: It delivers optimal performance.
Cross-platform development: You can develop both Android and iOS apps with it. The reuse of code expedites development and reduces costs.
UI design: React Native enables you to design simple and responsive UI for your mobile app.
3rd party plugins: This framework supports 3rd party plugins.
Developer community: A vibrant community of developers support React Native.

Why React Native is fundamentally different from earlier hybrid frameworks

Are you wondering whether React Native is just another of those hybrid frameworks like Ionic or Cordova? It’s not! React Native is fundamentally different from these earlier hybrid frameworks.

React Native is very close to native. Consider the following aspects as described on the React Native website:

Access to many native platforms features: The primitives of React Native render to native platform UI. This means that your React Native app will use many native platform APIs as native apps would do.
Near-native user experience: React Native provides several native components, and these are platform agnostic.
The ease of accessing native APIs: React Native uses a declarative UI paradigm. This enables React Native to interact easily with native platform APIs since React Native wraps existing native code.

Due to these factors, React Native offers many more advantages compared to those earlier hybrid frameworks. We now review them.

#android app #frontend #ios app #mobile app development #benefits of react native #is react native good for mobile app development #native vs #pros and cons of react native #react mobile development #react native development #react native experience #react native framework #react native ios vs android #react native pros and cons #react native vs android #react native vs native #react native vs native performance #react vs native #why react native #why use react native

Leonard Paucek

1653408000

React Hot Loader: Tweak React Components in Real Time.

React Hot Loader

Tweak React components in real time ⚛️⚡️

Watch Dan Abramov's talk on Hot Reloading with Time Travel.

Moving towards next step

React-Hot-Loader has been your friendly neighbour, living outside of React. But it has been limiting its powers and causing not the greatest experience. It's time to make a next step.

React-Hot-Loader is expected to be replaced by React Fast Refresh. Please remove React-Hot-Loader if Fast Refresh is currently supported on your environment.

React Native - supports Fast Refresh since 0.61.
parcel 2 - supports Fast Refresh since alpha 3.
webpack - supports Fast Refresh using a plugin.
other bundler - no support yet, use React-Hot-Loader
create-react-app - supports Fast Refresh with FAST_REFRESH env since 4.
next.js - supports Fast Refresh since 9.4

Install

npm install react-hot-loader

Note: You can safely install react-hot-loader as a regular dependency instead of a dev dependency as it automatically ensures it is not executed in production and the footprint is minimal.

Getting started

Add react-hot-loader/babel to your .babelrc:

// .babelrc
{
  "plugins": ["react-hot-loader/babel"]
}

Mark your root component as hot-exported:

// App.js
import { hot } from 'react-hot-loader/root';
const App = () => <div>Hello World!</div>;
export default hot(App);

Make sure react-hot-loader is required before react and react-dom:

or import 'react-hot-loader' in your main file (before React)
or prepend your webpack entry point with react-hot-loader/patch, for example:

// webpack.config.js
module.exports = {
  entry: ['react-hot-loader/patch', './src'],
  // ...
};

If you need hooks support, use @hot-loader/react-dom

Hook support

Hooks would be auto updated on HMR if they should be. There is only one condition for it - a non zero dependencies list.

❄️ useState(initialState); // will never updated (preserve state)
❄️ useEffect(effect); // no need to update, updated on every render
❄️ useEffect(effect, []); // "on mount" hook. "Not changing the past"
🔥 useEffect(effect, [anyDep]); // would be updated

🔥 useEffect(effect, ["hot"]); // the simplest way to make hook reloadable

Plus

any hook would be reloaded on a function body change. Enabled by default, controlled by reloadHooksOnBodyChange option.
you may configure RHL to reload any hook by setting reloadLifeCycleHooks option to true.

To disable hooks reloading - set configuration option:

import { setConfig } from 'react-hot-loader';

setConfig({
  reloadHooks: false,
});

With this option set all useEffects, useCallbacks and useMemo would be updated on Hot Module Replacement.

Hooks reset

Hooks would be reset if their order changes. Adding, removing or moving around would cause a local tree remount.

Babel plugin is required for this operation. Without it changing hook order would throw an error which would be propagated till the nearest class-based component.

`@hot-loader/react-dom`

@hot-loader/react-dom replaces the "react-dom" package of the same version, but with additional patches to support hot reloading.

There are 2 ways to install it:

Use yarn name resolution, so @hot-loader/react-dom would be installed instead of react-dom

yarn add react-dom@npm:@hot-loader/react-dom

Use webpack aliases

yarn add @hot-loader/react-dom

// webpack.config.js
module.exports = {
  // ...
  resolve: {
    alias: {
      'react-dom': '@hot-loader/react-dom',
    },
  },
};

Old API

Note: There is also an old version of hot, used prior to version 4.5.4. Please use the new one, as it is much more resilient to js errors that you may make during development.

Meanwhile, not all the bundlers are compatible with new /root API, for example parcel is not.

React-Hot-Load will throw an error, asking you to use the old API, if such incompatibility would be detected. It is almost the same, but you have to pass module inside hot.

import { hot } from 'react-hot-loader';
const App = () => <div>Hello World!</div>;
export default hot(module)(App);

Run webpack with Hot Module Replacement:

webpack-dev-server --hot

What about production?

The webpack patch, hot, Babel plugin, @hot-loader/react-dom etc. are all safe to use in production; they leave a minimal footprint, so there is no need to complicate your configuration based on the environment. Using the Babel plugin in production is even recommended because it switches to cleanup mode.

Just ensure that the production mode has been properly set, both as an environment variable and in your bundler. E.g. with webpack you would build your code by running something like:

NODE_ENV=production webpack --mode production

NODE_ENV=production is needed for the Babel plugin, while --mode production uses webpack.DefinePlugin to set process.env.NODE_ENV inside the compiled code itself, which is used by hot and @hot-loader/react-dom.

Make sure to watch your bundle size when implementing react-hot-loader to ensure that you did it correctly.

Limitations

(that's the goal) React-Hot-Loader would not change the past, only update the present - no lifecycle event would be called on component update. As a result, any code changes made to componentWillUnmount or componentDidMount would be ignored for already created components.
(that's the goal) React-Hot-Loader would not update any object, including component state.
(1%) React-Hot-Loader may not apply some changes made to a component's constructor. Unless an existing component is recreated, RHL would typically inject new data into that component, but there is no way to detect the actual change or the way it was applied, especially if the change was made to a function. This is because of the way React-Hot-Loader works - it knows what class functions are, not how they were created. See #1001 for details.

Recipes

Migrating from create-react-app

Run npm run eject
Install React Hot Loader (npm install --save-dev react-hot-loader)
In config/webpack.config.dev.js, add 'react-hot-loader/babel' to Babel loader configuration. The loader should now look like:

  {
    test: /\.(js|jsx)$/,
    include: paths.appSrc,
    loader: require.resolve('babel-loader'),
    options: {
      // This is a feature of `babel-loader` for webpack (not Babel itself).
      // It enables caching results in ./node_modules/.cache/babel-loader/
      // directory for faster rebuilds.
      cacheDirectory: true,
      plugins: ['react-hot-loader/babel'],
    },
  }

Mark your App (src/App.js) as hot-exported:

// ./containers/App.js
import React from 'react';
import { hot } from 'react-hot-loader';

const App = () => <div>Hello World!</div>;

export default hot(module)(App);

Migrating from create-react-app without ejecting

Users report, that it is possible to use react-app-rewire-hot-loader to setup React-hot-loader without ejecting.

TypeScript

As of version 4, React Hot Loader requires you to pass your code through Babel to transform it so that it can be hot-reloaded. This can be a pain point for TypeScript users, who usually do not need to integrate Babel as part of their build process.

Fortunately, it's simpler than it may seem! Babel will happily parse TypeScript syntax and can act as an alternative to the TypeScript compiler, so you can safely replace ts-loader or awesome-typescript-loader in your Webpack configuration with babel-loader. Babel won't typecheck your code, but you can use fork-ts-checker-webpack-plugin (and/or invoke tsc --noEmit) as part of your build process instead.

A sample configuration:

{
  // ...you'll probably need to configure the usual Webpack fields like "mode" and "entry", too.
  resolve: { extensions: [".ts", ".tsx", ".js", ".jsx"] },
  module: {
    rules: [
      {
        test: /\.(j|t)sx?$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader",
          options: {
            cacheDirectory: true,
            babelrc: false,
            presets: [
              [
                "@babel/preset-env",
                { targets: { browsers: "last 2 versions" } } // or whatever your project requires
              ],
              "@babel/preset-typescript",
              "@babel/preset-react"
            ],
            plugins: [
              // plugin-proposal-decorators is only needed if you're using experimental decorators in TypeScript
              ["@babel/plugin-proposal-decorators", { legacy: true }],
              ["@babel/plugin-proposal-class-properties", { loose: true }],
              "react-hot-loader/babel"
            ]
          }
        }
      }
    ]
  },
  plugins: [
    new ForkTsCheckerWebpackPlugin()
  ]
};

For a full example configuration of TypeScript with React Hot Loader and newest beta version of Babel, check here.

As an alternative to this approach, it's possible to chain Webpack loaders so that your code passes through Babel and then TypeScript (or TypeScript and then Babel), but this approach is not recommended as it is more complex and may be significantly less performant. Read more discussion here.

Parcel

Parcel supports Hot Module Reloading out of the box, just follow step 1 and 2 of Getting Started.

We also have a full example running Parcel + React Hot Loader.

Electron

You need something to mark your modules as hot in order to use React Hot Loader.

One way of doing this with Electron is to simply use webpack like any web-based project might do and the general guide above describes. See also this example Electron app.

A webpack-less way of doing it to use electron-compile (which is also used by electron-forge) - see this example. While it requires less configuration, something to keep in mind is that electron-compile's HMR will always reload all modules, regardless of what was actually edited.

Source Maps

If you use devtool: 'source-map' (or its equivalent), source maps will be emitted to hide hot reloading code.

Source maps slow down your project. Use devtool: 'eval' for best build performance.

Hot reloading code is just one line in the beginning and one line at the end of each module so you might not need source maps at all.

Linking

If you are using npm link or yarn link for development purposes, there is a chance you will get error Module not found: Error: Cannot resolve module 'react-hot-loader' or the linked package is not hot reloaded.

There are 2 ways to fix Module not found:

Use include in loader configuration to only opt-in your app's files to processing.
Alternatively if you are using webpack, override the module resolution in your config:

{
  resolve: {
    alias: {
      'react-hot-loader': path.resolve(path.join(__dirname, './node_modules/react-hot-loader')),
    }
  }
}

And to make your linked package to be hot reloaded, it will need to use the patched version of react and react-dom, if you're using webpack, add this options to the alias config

{
  resolve: {
    alias: {
      'react-hot-loader': path.resolve(path.join(__dirname, './node_modules/react-hot-loader')),
      // add these 2 lines below so linked package will reference the patched version of `react` and `react-dom`
      'react': path.resolve(path.join(__dirname, './node_modules/react')),
      'react-dom': path.resolve(path.join(__dirname, './node_modules/react-dom')),
      // or point react-dom above to './node_modules/@hot-loader/react-dom' if you are using it
    }
  }
}

Preact

React-hot-loader should work out of the box with preact-compat, but, in case of pure preact, you will need to configure it:

create configuration file (setupHotLoader.js)

import reactHotLoader from 'react-hot-loader';
import preact from 'preact';

reactHotLoader.preact(preact);

dont forget to import it

Preact limitations

HOCs and Decorators as not supported yet. For Preact React-Hot-Loader v4 behave as v3.

React Native

React Native supports hot reloading natively as of version 0.22.

Using React Hot Loader with React Native can cause unexpected issues (see #824) and is not recommended.

Webpack plugin

We recommend using the babel plugin, but there are some situations where you are unable to. If so, try the webpack plugin / webpack-loader (as seen in v3).

Remember - the webpack plugin is not compatible with class-based components. The babel plugin will inject special methods to every class, to make class members (like onClick) hot-updatable, while the webpack plugin would leave classes as is, without any instrumentation.

class MyComponent extends React.Component {
  onClick = () => this.setState(); // COULD NOT UPDATE
  variable = 1; // this is ok
  render() {} // this is ok
}

But webpack-loader could help with TypeScript or spreading "cold API" to all node_modules.

It is possible to enable this loader for all the files, but if you use babel plugin, you need to enable this loader for react-dom only. Place it after babel-loader, if babel-loader is present.

// webpack.config.js
module.exports = {
  module: {
    rules: [
      // would only land a "hot-patch" to react-dom
      {
        test: /\.js$/,
        include: /node_modules\/react-dom/,
        use: ['react-hot-loader/webpack'],
      },
    ],
  },
};

Webpack plugin will also land a "hot" patch to react-dom, making React-Hot-Loader more compliant to the principles.

If you are not using babel plugin you might need to apply webpack-loader to all the files.

{
  test: /\.jsx?$/,
  include: /node_modules/,
  use: ['react-hot-loader/webpack']
},

Code Splitting

If you want to use Code Splitting + React Hot Loader, the simplest solution is to pick a library compatible with this one:

If you use a not-yet-friendly library, like react-async-component, or are having problems with hot reloading failing to reload code-split components, you can manually mark the components below the code-split boundaries.

// AsyncHello.js
import { asyncComponent } from 'react-async-component';

// asyncComponent could not `hot-reload` itself.
const AsyncHello = asyncComponent({
  resolve: () => import('./Hello'),
});

export default AsyncHello;

Note that Hello is the component at the root of this particular code-split chunk.

// Hello.js
import { hot } from 'react-hot-loader/root';

const Hello = () => 'Hello';

export default hot(Hello); // <-- module will reload itself

Wrapping this root component with hot() will ensure that it is hot reloaded correctly.

Out-of-bound warning

You may see the following warning when code-split components are updated:

React-Hot-Loader: some components were updated out-of-bound. Updating your app to reconcile the changes.

This is because the hot reloading of code-split components happens asynchronously. If you had an App.js that implemented the AsyncHello component above and you modified AsyncHello, it would be bundled and reloaded at the same time as App.js. However, the core hot reloading logic is synchronous, meaning that it's possible for the hot reload to run before the updates to the split component have landed.

In this case, RHL uses a special tail update detection logic, where it notes that an an update to a split component has happened after the core hot reloading logic has already finished, and it triggers another update cycle to ensure that all changes are applied.

The warning is informational - it is a notice that this tail update logic is triggered, and does not indicate a problem in the configuration or useage of react-hot-loader.

If the tail update detection is not something you want or need, you can disable this behavior by setting setConfig({ trackTailUpdates:false }).

Checking Element `type`s

Because React Hot Loader creates proxied versions of your components, comparing reference types of elements won't work:

const element = <Component />;
console.log(element.type === Component); // false

React Hot Loader exposes a function areComponentsEqual to make it possible:

import { areComponentsEqual } from 'react-hot-loader';
const element = <Component />;
areComponentsEqual(element.type, Component); // true

Another way - compare "rendered" element type

const element = <Component />;
console.log(element.type === <Component />.type); // true

// better - precache rendered type
const element = <Component />;
const ComponentType = <Component />.type;
console.log(element.type === ComponentType); // true

But you might have to provide all required props. See original issue. This is most reliable way to compare components, but it will not work with required props.

Another way - compare Component name.

Not all components have a name. In production displayName could not exists.

const element = <Component />;
console.log(element.displayName === 'Component'); // true

This is something we did not solve yet. Cold API could help keep original types.

Webpack ExtractTextPlugin

webpack ExtractTextPlugin is not compatible with React Hot Loader. Please disable it in development:

new ExtractTextPlugin({
  filename: 'styles/[name].[contenthash].css',
  disable: NODE_ENV !== 'production',
});

Disabling a type change (❄️)

It is possible to disable React-Hot-Loader for a specific component, especially to enable common way to type comparison. See #991 for the idea behind ⛄️, and #304 about "type comparison" problem.

import { cold } from 'react-hot-loader';

cold(SomeComponent) // this component will ignored by React-Hot-Loader
<SomeComponent />.type === SomeComponent // true

If you will update cold component React-Hot-Loader will complain (on error level), and then React will cold-replace Component with a internal state lose.

Reach-Hot-Loader: cold element got updated

Disabling a type change for all node_modules

You may cold all components from node_modules. This will not work for HOC(like Redux) or dynamically created Components, but might help in most of situations, when type changes are not welcomed, and modules are not expected to change.

import { setConfig, cold } from 'react-hot-loader';
setConfig({
  onComponentRegister: (type, name, file) => file.indexOf('node_modules') > 0 && cold(type),

  // some components are not visible as top level variables,
  // thus its not known where they were created
  onComponentCreate: (type, name) => name.indexOf('styled') > 0 && cold(type),
});

! To be able to "cold" components from 'node_modules' you have to apply babel to node_modules, while this folder is usually excluded. You may add one more babel-loader, with only one React-Hot-Loader plugin inside to solve this. Consider using webpack-loader for this.

React-Hooks

React hooks are not really supported by React-Hot-Loader. Mostly due to our internal processes of re-rendering React Tree, which is required to reconcile an updated application before React will try to rerender it, and fail to do that, obviously.

hooks should work for versions 4.6.0 and above (pureSFC is enabled by default).
hooks will produce errors on every hot-update without patches to react-dom.
hooks may loss the state without patches to react-dom.
hooks does not support adding new hooks on the fly
change in hooks for a mounted components will cause a runtime exception, and a retry button (at the nearest class component) will be shown. Pressing a retry button will basically remount tree branch.

To mitigate any hook-related issues (and disable their hot-reloadability) - cold them.

cold components using hooks.

import { setConfig, cold } from 'react-hot-loader';
setConfig({
  onComponentCreate: (type, name) =>
    (String(type).indexOf('useState') > 0 || String(type).indexOf('useEffect') > 0) && cold(type),
});

API

`hot(Component, options)`

Mark a component as hot.

Babel plugin

Right now babel plugin has only one option, enabled by default.

safetyNet - will help you properly setup ReactHotLoader.

You may disable it to get more control on the module execution order.

//.babelrc
{
    "plugins": [
        [
            "react-hot-loader/babel",
            {
            "safetyNet": false
            }
        ]
    ]
}

Important

!! Use hot only for module exports, not for module imports. !!

import { hot } from 'react-hot-loader/root';

const App = () => 'Hello World!';

export default hot(App);

Keep in mind - by importing react-hot-loader/root you are setting up a boundary for update event propagation.

The higher(in module hierarchy) you have it - the more stuff would be updated on Hot Module Replacement.

To make RHL more reliable and safe, please place hot below (ie somewhere in imported modules):

react-dom
redux store creation
any data, you want to preserve between updates
big libraries

You may(but it's not required) place hot to the every route/page/feature/lazy chunk, thus make updates more scoped.

You don't need to wrap every component with hot, application work work fine with a single one.

(old)`hot(module, options)(Component, options)`

Mark a component as hot. The "new" hot is just hidding the first part - hot(module), giving you only the second (App). The "new" hot is using old API.

import { hot } from 'react-hot-loader';

const App = () => 'Hello World!';

export default hot(module)(App);

`AppContainer`

Mark application as hot reloadable. (Prefer using hot helper, see below for migration details).

This low-level approach lets you make **hot **imports__, not exports.

import React from 'react';
import ReactDOM from 'react-dom';
import { AppContainer } from 'react-hot-loader';
import App from './containers/App';

const render = Component => {
  ReactDOM.render(
    <AppContainer>
      <Component />
    </AppContainer>,
    document.getElementById('root'),
  );
};

render(App);

// webpack Hot Module Replacement API
if (module.hot) {
  // keep in mind - here you are configuring HMR to accept CHILDREN MODULE
  // while `hot` would configure HMR for the CURRENT module
  module.hot.accept('./containers/App', () => {
    // if you are using harmony modules ({modules:false})
    render(App);
    // in all other cases - re-require App manually
    render(require('./containers/App'));
  });
}

areComponentsEqual(Component1, Component2)

Test if two components have the same type.

import { areComponentsEqual } from 'react-hot-loader';
import Component1 from './Component1';
import Component2 from './Component2';

areComponentsEqual(Component1, Component2); // true or false

setConfig(config)

Set a new configuration for React Hot Loader.

Available options are:

logLevel: specify log level, default to "error", available values are: ['debug', 'log', 'warn', 'error']
pureSFC: enable Stateless Functional Component. If disabled they will be converted to React Components. Default value: false.
ignoreSFC: skip "patch" for SFC. "Hot loading" could still work, with webpack-patch present
pureRender: do not amend render method of any component.
for the rest see index.d.ts.

// rhlConfig.js
import { setConfig } from 'react-hot-loader';

setConfig({ logLevel: 'debug' });

It is important to set configuration before any other action will take a place

// index.js
import './rhlConfig' // <-- extract configuration to a separate file, and import it in the beggining
import React from 'react'
....

Migrating from v3

AppContainer vs hot

Prior v4 the right way to setup React Hot Loader was to wrap your Application with AppContainer, set setup module acceptance by yourself. This approach is still valid but only for advanced use cases, prefer using hot helper.

React Hot Loader v3:

// App.js
import React from 'react';

const App = () => <div>Hello world!</div>;

export default App;

// main.js
import React from 'react';
import ReactDOM from 'react-dom';
import { AppContainer } from 'react-hot-loader';
import App from './containers/App';

const render = Component => {
  ReactDOM.render(
    <AppContainer>
      <Component />
    </AppContainer>,
    document.getElementById('root'),
  );
};

render(App);

// webpack Hot Module Replacement API
if (module.hot) {
  module.hot.accept('./containers/App', () => {
    // if you are using harmony modules ({modules:false})
    render(App);
    // in all other cases - re-require App manually
    render(require('./containers/App'));
  });
}

React Hot Loader v4:

// App.js
import React from 'react';
import { hot } from 'react-hot-loader';

const App = () => <div>Hello world!</div>;

export default hot(module)(App);

// main.js
import React from 'react';
import ReactDOM from 'react-dom';
import App from './containers/App';

ReactDOM.render(<App />, document.getElementById('root'));

Patch is optional

Since 4.0 till 4.8

Code is automatically patched, you can safely remove react-hot-loader/patch from your webpack config, if react-hot-loader is required before React in any other way.

Error Boundary is inside every component

Since 4.5.4

On Hot Module Update we will inject componentDidCatch and a special render to every Class-based component you have, making Error Boundaries more local.

After update we will remove all sugar, keeping only Boundaries you've created.

You can provide your own errorReporter, via setConfig({errorReporter}) or opt-out from root ErrorBoundaries setting errorBoundary={false} prop on AppContainer or hot. However - this option affects only SFC behavior, and any ClassComponent would boundary itself.

import { setConfig } from 'react-hot-loader';
import ErrorBoundary from './ErrorBoundary';

// ErrorBoundary will be given error and errorInfo prop.
setConfig({ errorReporter: ErrorBoundary });

If errorReporter is not set - full screen error overlay would be shown.

Setting global Error Reporter

Global Error Reporter would, created a fixed overlay on top the page, would be used to display errors, not handled by errorReporter, and any HMR error.

You may change, or disable this global error overlay

// to disable
setConfig({ ErrorOverlay: () => null });

// to change
setConfig({ ErrorOverlay: MyErrorOverlay });

The UX of existing overlay is a subject to change, and we are open to any proposals.

Known limitations and side effects

Note about `hot`

hot accepts only React Component (Stateful or Stateless), resulting the HotExported variant of it. The hot function will setup current module to self-accept itself on reload, and will ignore all the changes, made for non-React components. You may mark as many modules as you want. But HotExportedComponent should be the only used export of a hot-module.

Note: Please note how often we have used exported keyword. hot is for exports.

Note: Does nothing in production mode, just passes App through.

New Components keep executing the old code

There is no way to hot-update constructor code, as result even new components will be born as the first ones, and then grow into the last ones. As of today, this issue cannot be solved.

Troubleshooting

If it doesn't work, in 99% of cases it's a configuration issue. A missing option, a wrong path or port. webpack is very strict about configuration, and the best way to find out what's wrong is to compare your project to an already working setup, check out examples, bit by bit.

If something doesn't work, in 99% of cases it's an issue with your code. The Component didn't get registered, due to HOC or Decorator around it, which is making it invisible to the Babel plugin or webpack loader.

We're also gathering Troubleshooting Recipes so send a PR if you have a lesson to share!

Switch into debug mode

Debug mode adds additional warnings and can tells you why React Hot Loader is not working properly in your application.

import { setConfig } from 'react-hot-loader';
setConfig({ logLevel: 'debug' });

Author: gaearon
Source Code: https://github.com/gaearon/react-hot-loader
License: MIT license

#react-native #react

Ian Robinson

1621644000

4 Real-Time Data Analytics Predictions for 2021

Data management, analytics, data science, and real-time systems will converge this year enabling new automated and self-learning solutions for real-time business operations.

The global pandemic of 2020 has upended social behaviors and business operations. Working from home is the new normal for many, and technology has accelerated and opened new lines of business. Retail and travel have been hit hard, and tech-savvy companies are reinventing e-commerce and in-store channels to survive and thrive. In biotech, pharma, and healthcare, analytics command centers have become the center of operations, much like network operation centers in transport and logistics during pre-COVID times.

While data management and analytics have been critical to strategy and growth over the last decade, COVID-19 has propelled these functions into the center of business operations. Data science and analytics have become a focal point for business leaders to make critical decisions like how to adapt business in this new order of supply and demand and forecast what lies ahead.

In the next year, I anticipate a convergence of data, analytics, integration, and DevOps to create an environment for rapid development of AI-infused applications to address business challenges and opportunities. We will see a proliferation of API-led microservices developer environments for real-time data integration, and the emergence of data hubs as a bridge between at-rest and in-motion data assets, and event-enabled analytics with deeper collaboration between data scientists, DevOps, and ModelOps developers. From this, an ML engineer persona will emerge.

#analytics #artificial intelligence technologies #big data #big data analysis tools #from our experts #machine learning #real-time decisions #real-time analytics #real-time data #real-time data analytics

Jessica Smith

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REAL TIME CHAT SOLUTIONS SERVICES FOR MOBILE APPS

Build a Real Time chat application that can integrated into your social handles. Add more life to your website or support portal with a real time chat solutions for mobile apps that shows online presence indicators, typing status, timestamp, multimedia sharing and much more. Users can also log into the live chat app using their social media logins sparing them from the need to remember usernames and passwords. For more information call us at +18444455767 or email us at hello@sisgain.com or Visit: https://sisgain.com/instant-real-time-chat-solutions-mobile-apps

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Mathew Rini

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How to Select and Hire the Best React JS and React Native Developers?

Since March 2020 reached 556 million monthly downloads have increased, It shows that React JS has been steadily growing. React.js also provides a desirable amount of pliancy and efficiency for developing innovative solutions with interactive user interfaces. It’s no surprise that an increasing number of businesses are adopting this technology. How do you select and recruit React.js developers who will propel your project forward? How much does a React developer make? We’ll bring you here all the details you need.

What is React.js?

Facebook built and maintains React.js, an open-source JavaScript library for designing development tools. React.js is used to create single-page applications (SPAs) that can be used in conjunction with React Native to develop native cross-platform apps.

React vs React Native

React Native is a platform that uses a collection of mobile-specific components provided by the React kit, while React.js is a JavaScript-based library.
React.js and React Native have similar syntax and workflows, but their implementation is quite different.
React Native is designed to create native mobile apps that are distinct from those created in Objective-C or Java. React, on the other hand, can be used to develop web apps, hybrid and mobile & desktop applications.
React Native, in essence, takes the same conceptual UI cornerstones as standard iOS and Android apps and assembles them using React.js syntax to create a rich mobile experience.

What is the Average React Developer Salary?

In the United States, the average React developer salary is $94,205 a year, or $30-$48 per hour, This is one of the highest among JavaScript developers. The starting salary for junior React.js developers is $60,510 per year, rising to $112,480 for senior roles.

* React.js Developer Salary by Country

United States- $120,000
Canada - $110,000
United Kingdom - $71,820
The Netherlands $49,095
Spain - $35,423.00
France - $44,284
Ukraine - $28,990
India - $9,843
Sweden - $55,173
Singapore - $43,801

In context of software developer wage rates, the United States continues to lead. In high-tech cities like San Francisco and New York, average React developer salaries will hit $98K and $114per year, overall.

However, the need for React.js and React Native developer is outpacing local labour markets. As a result, many businesses have difficulty locating and recruiting them locally.

It’s no surprise that for US and European companies looking for professional and budget engineers, offshore regions like India are becoming especially interesting. This area has a large number of app development companies, a good rate with quality, and a good pool of React.js front-end developers.

As per Linkedin, the country’s IT industry employs over a million React specialists. Furthermore, for the same or less money than hiring a React.js programmer locally, you may recruit someone with much expertise and a broader technical stack.

How to Hire React.js Developers?

Conduct thorough candidate research, including portfolios and areas of expertise.
Before you sit down with your interviewing panel, do some homework.
Examine the final outcome and hire the ideal candidate.

Why is React.js Popular?

React is a very strong framework. React.js makes use of a powerful synchronization method known as Virtual DOM, which compares the current page architecture to the expected page architecture and updates the appropriate components as long as the user input.

React is scalable. it utilises a single language, For server-client side, and mobile platform.

React is steady.React.js is completely adaptable, which means it seldom, if ever, updates the user interface. This enables legacy projects to be updated to the most new edition of React.js without having to change the codebase or make a few small changes.

React is adaptable. It can be conveniently paired with various state administrators (e.g., Redux, Flux, Alt or Reflux) and can be used to implement a number of architectural patterns.

Is there a market for React.js programmers?
The need for React.js developers is rising at an unparalleled rate. React.js is currently used by over one million websites around the world. React is used by Fortune 400+ businesses and popular companies such as Facebook, Twitter, Glassdoor and Cloudflare.

Final thoughts:

As you’ve seen, locating and Hire React js Developer and Hire React Native developer is a difficult challenge. You will have less challenges selecting the correct fit for your projects if you identify growing offshore locations (e.g. India) and take into consideration the details above.

If you want to make this process easier, You can visit our website for more, or else to write a email, we’ll help you to finding top rated React.js and React Native developers easier and with strives to create this operation

#hire-react-js-developer #hire-react-native-developer #react #react-native #react-js #hire-react-js-programmer

React Hot Loader: Tweak React Components in Real Time.

React Hot Loader

Install

Getting started

Hook support

Hooks reset

@hot-loader/react-dom

Old API

What about production?

Limitations

Recipes

Migrating from create-react-app

Migrating from create-react-app without ejecting

TypeScript

Parcel

Electron

Source Maps

Linking

Preact

Preact limitations

React Native

Webpack plugin

Code Splitting

Out-of-bound warning

Checking Element types

Webpack ExtractTextPlugin

Disabling a type change (❄️)

API

hot(Component, options)

Babel plugin

Important

(old)hot(module, options)(Component, options)

AppContainer

areComponentsEqual(Component1, Component2)

setConfig(config)

Migrating from v3

AppContainer vs hot

Patch is optional

Error Boundary is inside every component

Setting global Error Reporter

Known limitations and side effects

Note about hot

New Components keep executing the old code

Troubleshooting

Switch into debug mode

What is GEEK

Buddha Community

How native is React Native? | React Native vs Native App Development

A brief introduction to React Native

Why React Native is fundamentally different from earlier hybrid frameworks

React Hot Loader: Tweak React Components in Real Time.

React Hot Loader

Install

Getting started

Hook support

Hooks reset

@hot-loader/react-dom

Old API

What about production?

Limitations

Recipes

Migrating from create-react-app

Migrating from create-react-app without ejecting

TypeScript

Parcel

Electron

Source Maps

Linking

Preact

Preact limitations

React Native

Webpack plugin

Code Splitting

Out-of-bound warning

Checking Element types

Webpack ExtractTextPlugin

Disabling a type change (❄️)

API

hot(Component, options)

Babel plugin

`@hot-loader/react-dom`

Checking Element `type`s

`hot(Component, options)`

(old)`hot(module, options)(Component, options)`

`AppContainer`

Note about `hot`

`@hot-loader/react-dom`

Checking Element `type`s

`hot(Component, options)`

(old)`hot(module, options)(Component, options)`

`AppContainer`

Note about `hot`