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React is one of the web’s most popular frameworks for building JavaScript applications. 

If you know what you’re doing, React can drastically simplify how you build, use, and maintain code.

Whether you’re a React newbie or you’re ready for advanced techniques, you can level-up with egghead. Explore our in-depth courses, lessons, and community resources to build more powerful applications and crack open your career.

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Progressive Web Apps can speed up app loading times, and even allow you to run your web app offline, and install it on a mobile device!  However, setting up a PWA correctly can be tricky.

In this course, we'll create a PWA from start to finish, using create-react-app.  We'll create a custom service worker, and use different caching strategies for different types of assets.

Finally, we'll look at how to install the app on both iOS and Android devices, and how to customize the app name, icon, and splash screen.

Course Introduction: Progressive Web Apps in React with create-react-app

React Native lets you build mobile apps using only JavaScript. It uses the same design as React, letting you compose a rich mobile UI from declarative components.

react-native

Learn to write components that render differently on iOS and Android, but present the same API. First, we'll use the Platform module to change behavior based on the platform. Then, we'll use the platform-specific file extensions, .ios.js and .android.js, to render platform-specific components.


Writing Platform-Specific Components for iOS and Android in React Native

In this lesson, we will start with a list of content from a React Native FlatList that we will then transform into a three-per-row grid.

Display Contents of a React Native FlatList as a Grid

In this lesson, you will learn how to use the `SafeAreaView` component to avoid the sensor cluster (the notch) and home activity indicator on the iPhone X.

Use the SafeAreaView Component in React Native for iPhone X Compatibility

First, install redux with: `npm install --save redux` and install react-redux with: `npm install --save react-redux`

In the top level of your component tree, import `createStore` from redux, and use it to create a new store with a simple reducer:

`import { createStore } from 'redux'`

`const rootReducer = (state = {}, action) => {
  return state
}`

`const store = createStore(rootReducer)`

Also import `Provider` from react-redux:

`import { Provider } from 'react-redux'`

And then wrap your app's components with a `Provider` component, and pass in your `store` as a prop:

`<Provider store={store}>`
  `...`
`</Provider>`

Then, you can connect any sub components with the `connect` function, by first importing it:

`import { connect } from 'react-redux'`

And then calling it with a `mapStateToProps` or `mapDispatchToProps` argument, and then passing in the unconnected component:

`const ConnectedLoginGate = connect(state => ({
  username: state.auth.username
}))(LoginGate)`





Add Redux to an Existing React Native Application

iOS and Android come with several built in fonts, but if you want to use a custom font in your react native application, you'll need to add it first.

You can add a custom font by copying the font files to your project, telling react native where to find those files by adding an `rnpm` entry to your `package.json` file, and then linking them with `react-native link`. 

Then, you can use that new font by specify it as the `fontFamily` style for a `Text` component, and you can change the `fontWeight` or `fontStyle` component if you've added additional style and weight font files.



Add a Custom Font to a React Native Application

There are two ways to open urls in React Native.  One is to open, and switch to the device's web browser, and the other is to embed the web page within your application.

To open the mobile device's web browser, we'll import `Linking` from react native, and use the `openURL` function, which will open any url that starts with `http` or `https` in that web browser.

If you want to stay within your current application however,  you can import `WebView` from react native, and use that as a component in your application.  Pass in a `uri` param to display that web page in the embedded web view.

Open a Webpage in React Native with Linking and WebView

When you bring up the on screen keyboard in a mobile app, it will cover any text input or buttons on the bottom half of the screen, which can be frustrating for users.  There are a few common ways to deal with this in React Native - and this video shows the following solutions:

First, you can use the built in `KeyboardAvoidingView` to move components around when the keyboard comes on screen.  It has the advantage to being built in to React Native already - but it can be overly complicated to get this approach to work consistently across both iOS and Android.

There is also a third party library called `KeyboardAwareScrollView`, which will allow your entire view to scroll, and will keep the currently selected text inputs up and out of the way of the keyboard.

Prevent the On-screen Keyboard from Covering up Text Inputs

We’ll create a brand new React Native app, and get it to launch on the iOS simulator and Android emulator.  A Mac is required to build for iOS, but Android development can be done on Mac, Windows, or Linux.

Create a React Native App and Run it on the iOS Simulator and Android Emulator

Once your React Native app is up and running, we’ll make a simple change and reload the simulator to show the change.  We’ll look at manually reloading the simulator, reloading with Live Reload and reloading with Hot Reloading, and talk about the pros and cons of each method.

Reload the Simulator when Changes Occur in React Native Apps

Displaying text is a key component of mobile apps, so we’ll look at how to show text on the screen, and how it differs from text on the web.  We’ll also format the text style to change the size, alignment, and more.

Display and Format Text in a React Native Application

React Native uses Flexbox to layout most components, which makes it easy to run your app on devices of many different screen sizes.  We’ll learn the basics of Flexbox in React Native, and how to use it to build a flexible screen layout.  We’ll also look at some differences between flexbox on the web and on mobile.

Layout React Native Components with Flexbox

One way to style React Native components is with a `StyleSheet`, which was designed to be similar to css.  We’ll go over the differences between React Native styles and web styles, and we’ll create a new StyleSheet, and use it to change the style of components in our app.

Style Components in a React Native App with StyleSheet

In this lesson, we’ll accept user input for the first time with a text box.  We’ll operate the text input as a controlled component, and store the text value in our component state.  We’ll use that text input to perform a live search on the elements in the list.

Accept User Input with React Native TextInput

We’ll turn on remote debugging in the simulator, and log values to the console.  We’ll also look at the differences between `log`, `warn` and `error`, and turn off the yellow warning box in the simulator itself.

Write to the Console Log in a React Native App

React Native applications can be debugged with the Chrome debugger by inserting a `debugger` command in React Native.  Then, you can see all the variables and their values in the current scope, and even change the values, and continue execution.  We’ll also use breakpoints in the debugger, and learn how to pause on exceptions - all of which can be used to better understand what is happening during an error or exception case.

Use the Debugger in a React Native App

Most React Native code is shared between iOS and Android, but sometimes there is a need for different styling on each platform, or to have completely different code run on each device.  We’ll look at three different ways to change styles or entire components between iOS and Android.

Style React Native Components Differently on iOS and Android

There’s no required folder structure for React Native applications, but we’ll structure our app with some common folder guidelines.  Then, we’ll create a `package.json` file for each sub-folder, which allows us to import components using absolute references like `components/Header` instead of relative paths like `../../../components/Header`.

Clean Up the Folder Structure and Imports in a React Native App with Absolute Paths

Screens on mobile devices don’t automatically scroll like the web.  To let the user scroll the screen, we’ll wrap our screen in a `ScrollView`.

Scroll Elements on a React Native Screen with ScrollView

Using `ScrollView` is an easy way to scroll a list, but it isn’t the most memory efficient, which can really matter for performance on devices with limited memory.  We’ll switch from using `ScrollView` to using `FlatList`, which will reuse views, and is the preferred way of showing long scrollable lists.

Display a List of Items in React Native with FlatList

Touchable buttons are all over mobile applications, so we’ll look at how to make a few different styles of buttons in React Native.  Unlike on the web, not every component type accepts an `onPress` prop, so we’ll look at how to wrap other components in a `Touchable` element in order to make a button.

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Android