Modern React with Redux [2020 Update]

• Get current node version

node -v

• Install the tool that will help us create new React Apps

  • npm install -g create-react-app
    • npm node package manager, just like composer for php
    • install the command to install new packages
    • -g install the package globaly so we can use the terminal to create new apps
    • create-react-app the package name reade more

• After installing create-react-app globaly, we can create new app via the command line:

  • We can use this command: create-react-app modern-react-with-redux

  • Or this command: npx create-react-app modern-react-with-redux

    • npx comes with npm 5.2+ and higher

• npm start

  • This command will start our app which will be available on: http://localhost:3000

• Babel: is a toolchain that is mainly used to convert ECMAScript 2015+ code into a backwards compatible version of JavaScript in current and older browsers or environments.

Lesson 9

• /src/index.js

  • Import the React and ReactDOM libraries

    import React from 'react';
    import ReactDOM from 'react-dom';

    • import: We want to get code from other file or dependency
    • React, ReactDOM... : The variable we want to assign this import to
    • from: We are about to specify the name of the library or file we are importing from
    • react, react-dom... : The name of the dependency or path to the file we are importing

• import / require

  • import is used with ES2015 modules
  • require is used with CommonJS modules

Lesson 10

• A component is: function or Class

  • produces HTML to show to the user (using JSX)
  • and handles feedback from the user (using Event Handlers)

• Example of function component:

const App = () => {
  return <div> Hi there!</div>;
}

ReactDOM.render(
  <App />,
  document.querySelector("#root"); 
);
  

Lesson 11

• An example of JSX transformed to JS using babel.

Lesson 12

• JSX

  • Special dialect of JS (its not HTML!)
  • Browsers don't understand JSX code! We write JSX then run tools to turn it into normal JS
  • Very similar in form and function to HTML with couple differences

• There is a convention for writing multiline JSX

  • Add parentheses after return and start JSX on new line

  return (
    <div>
        <label for="name">Enter name</label>
        <input id="name" type="text" />
    </div>
  );

Lesson 13 to Lesson 18

• JSX VS HTML

  • Adding custom styling to an element uses different syntax

    • HTML

    <div style="background-color:red;"></div>"

    • JSX style is an object: replace kebab-case keys with camelCase and add quotes to values (String)

    <div style={{backgroundColor:'red'}}></div>"

  • Adding class to an element uses different syntax

    • HTML

    <div class="example"></div>

    • JSX: we use className instead of class

    <div className ="example"></div>

  • JSX can reference JS variables

    • We can print JS variables inside JSX block.
      • Example1: buttonText

      const buttonText = 'Click me!';
      
      return (
        <div>
            <label for="name">Enter name</label>
            <input id="name" type="text" />
            
            <button> {buttonText} </button>
        </div>
      );

      • Example2: getButtonText()

      function getButtonText() {
        return 'Click on me!';
      }
      
      const App = () => {
          return (
            <div>
                <label for="name">Enter name</label>
                <input id="name" type="text" />
                
                <button> {getButtonText()} </button>
            </div>
          );
      };

      • PS: we can print content {buttonText} if its value is an Array or String but when it's an object we must get valid element inside this object

        // example: 
        buttonText = {'title': 'something'}
        // valid inside JSX
        {buttonText.title} 
        // the following will throw an error: Objects are not a valid React child...
        {buttonText}

  • Attribute name for will throw a warning => we must use `htmlFor'

    // Wrong
    const App = () => {
        return (
          <div>
              <label for="name">Enter name</label>
              <input id="name" type="text" />
              
              <button> {getButtonText()} </button>
          </div>
        );
    };

    // Right
    const App = () => {
        return (
          <div>
              <label htmlFor="name">Enter name</label>
              <input id="name" type="text" />
              
              <button> {getButtonText()} </button>
          </div>
        );
    };

Lesson 25

• Install faker library

  npm install --save faker

  • --save : will save the library into our project (added to package.json file)

• To use faker library:

  // import the lib
  import faker from 'faker';
  
  // ....
  // Inside JSX
  <img src={faker.image.avatar} />

  • Faker documentation

Lesson 28

• Component nesting

  • import : import CommentDetail form './CommentDetail';
  • export : export default CommentDetail;

• If we want to show a component inside another we're gonna treat it as it was a JSX tag <CommentDetail />

return (
    <div>
        <CommentDetail />
    </div>
);

Lesson 29

• props (properties)

  • System for passing data from a parent component to a child component
  • => Goal is to customize or configure a child component

• Providing props from parent to child

  <CommentDetail author="Oussama" />

  • author : name of the prop
  • Oussama : Value of the prop
    • We could pass a var instead of hardcoded string <CommentDetail author={someVar} />

• Consume props in child component

  const CommentDetail = props => {
  
    return (
        <div>
          <span>{props.author}</span>
        </div>
    );
  
  };

Lesson 35

• Component reuse (ApprovalCard)

  const ApprovalCard = (props) => {
    return (
        <div className="ui card">
          <div className="content">
            {props.children}
          </div>
          <div className="extra content">
            <div className="ui two buttons">
              <div className="ui basic green button">Approve</div>
              <div className="ui basic red button">Decline</div>
            </div>
          </div>
        </div>
    )
  };

  • In following code, CommentDetail will be nested inside ApprovalCard: {props.children}

  <ApprovalCard>
    <CommentDetail
        author="Oussama"
        timeAgo="Today at 6:00AM"
        content="Nice blog post!"
        avatar={faker.image.avatar()}
    />
  </ApprovalCard>

  • We can also use ApprovalCard this way:

  <ApprovalCard>
      Are you sure you want to do this?
  </ApprovalCard>

  <ApprovalCard>
      <div> 
          <h4>Warning!</h4>  
          Are you sure you want to do this?
      </div>
  </ApprovalCard>

Lesson 41

• Components:
  • Functional Components
    • Good for simple components
  • Class Components
    • Good for everything else
      • Easier code organization
      • Can use state => Easier to handle user input
      • Understands lifecycle events => Easier to do things when the app first starts

Lesson 42

• App Challenges (/2-second-project)
  • Need to get the users physical location
  • Need to determine the current month
  • Need to change text and styling based on location + month

npx create-react-app 2-second-project

Lesson 46

const App = () => {
  window.navigator.geolocation.getCurrentPosition(
      position => console.log(position),
      err => console.log(err)
  );

  return <div>Latitude: </div>
};

• Execution of our application explained in timeline
  • 1 - JS file loaded by browser
  • 2 - App component gets created
  • 3 - We call geolocation service => takes time to get results!!!
  • 4 - App returns JSX, gets rendered to page HTML
  • 5 - ...
  • 6 - We get result of geolocation !
    • => So the problem is that our content is rendered then the result of geolocation come later in time !!! That's why we need class component in conjunction with react's state system !

Lesson 47

• Rules of Class Component

  • Must be a javascript Class (ES2015)

  • Must extend (subclass) React.Component

  • Must define render method that returns some amount of JSX

    class App extends React.Component {
      render() {
        window.navigator.geolocation.getCurrentPosition(
            position => console.log(position),
            err => console.log(err)
        );
    
        return <div>Latitude: </div>
      }
    }

Lesson 48

• Rules of State
  • Only usable with class components technically can be used with functional components using the 'hooks' system
  • You will confuse props with state :(
  • State is JS object that contains data relevant to a component
  • Updating state on a component causes the component to (almost) instantlt rerender
  • State must be initialized when a component is created
  • State can ONLY be updated using the function setState

Lesson 49

• Adding local state to a class

class App extends React.Component {
  constructor () {
    super(props)
  }
  
  render() {
    window.navigator.geolocation.getCurrentPosition(
        position => console.log(position),
        err => console.log(err)
    );

    return <div>Latitude: </div>
  }
}

• The constructor method is a special method for creating and initializing an object created within a class.
  • A constructor enables you to provide any custom initialization that must be done before any other methods can be called on an instantiated object.
• The super keyword is used to access and call functions on an object's parent.

Lesson 50

• IMPORTANT:

  • We update our stat using setState()
  • We only use this.state = {} when defining initial state

• In lesson 48 we said:

  • State must be initialized when a component is created
  • State can ONLY be updated using the function setState

class App extends React.Component {
  constructor(props) {
    super(props);

    // THIS IS THE ONLY TIME we do direct assignment
    // to this.state
    this.state = {lat: null};

    window.navigator.geolocation.getCurrentPosition(
        position => {
          // we called setState !!! NOT this.state.lat = .... !!!
          this.setState({lat: position.coords.latitude})
        },
        err => console.log(err)
    );

  }

  render() {
    return <div>Latitude: {this.state.lat}</div>
  }
}

Original README.md Content

This project was bootstrapped with Create React App.

Available Scripts

In the project directory, you can run:

npm start

Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.

The page will reload if you make edits.
You will also see any lint errors in the console.

npm test

Launches the test runner in the interactive watch mode.
See the section about running tests for more information.

npm run build

Builds the app for production to the build folder.
It correctly bundles React in production mode and optimizes the build for the best performance.

The build is minified and the filenames include the hashes.
Your app is ready to be deployed!

See the section about deployment for more information.

npm run eject

Note: this is a one-way operation. Once you eject, you can’t go back!

If you aren’t satisfied with the build tool and configuration choices, you can eject at any time. This command will remove the single build dependency from your project.

Instead, it will copy all the configuration files and the transitive dependencies (webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except eject will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.

You don’t have to ever use eject. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.

Learn More

You can learn more in the Create React App documentation.

To learn React, check out the React documentation.

Code Splitting

This section has moved here: https://facebook.github.io/create-react-app/docs/code-splitting

Analyzing the Bundle Size

This section has moved here: https://facebook.github.io/create-react-app/docs/analyzing-the-bundle-size

Making a Progressive Web App

This section has moved here: https://facebook.github.io/create-react-app/docs/making-a-progressive-web-app

Advanced Configuration

This section has moved here: https://facebook.github.io/create-react-app/docs/advanced-configuration

Deployment

This section has moved here: https://facebook.github.io/create-react-app/docs/deployment

npm run build fails to minify

This section has moved here: https://facebook.github.io/create-react-app/docs/troubleshooting#npm-run-build-fails-to-minify