# switch to starter branch to get new starter code
git checkout starter

# download new starter code
git pull

# switch back to main branch for coding
git checkout main

# merge in new starter code (use default msg)
git merge starter --no-edit

# code and enjoy!

# Make sure you are in the project directory
cd path/to/project

# Install dependencies for existing project (installs vite)
npm install

# Run the development server script
npm run dev

//declare a function to define a component -- this is like a class
function HelloMessage(props) {

  
  //this function returns the elements (JSX)
  //that make up the component
  return (
     <h1>Hello World!</h1>
  );
}

//"call" function to create a new element value!
const msgElem = <HelloMessage />;

//show the content in the web page (inside #root)
const root = ReactDOM.createRoot(document.getElementById('root'));
root.render(msgElem)

# you must be in the React project folder
cd path/to/my-react-app

# install dependency
npm install bootstrap

/* in index.js */
import 'bootstrap/dist/css/bootstrap.css';
import 'my-style.css' // import your stylesheet afterwards

function MessageItem(props) {
   const message = props.message; //access the prop



    //can use prop for logic or processing
   const messageUpper = message.toUpperCase(); 

   return <li>{messageUpper}</li>; //render based on prop
}

ReactDOM.createRoot(document.getElementById('root'))
   .render(<MessageItem message="Be quiet" />)

function MessageList(props) {
  //msgComponents will be an array of components!
  const msgComponents = props.messages.map((msgStr) => {
    const elem = <MessageItem message={msgStr} key={msgStr} />; //pass prop down!
    return elem
  }

  return (
    <ul>
      {/* An array of components renders as siblings */}
      {msgComponents} 
    </ul>
  );
}

const messagesArray = ["Hello world", "No borders", "Go huskies!"];

ReactDOM.createRoot(document.getElementById('root'))
   .render(<MessageList messages={messagesArray} />)

function ConditionalPanel(props) {
  //assign element to show to variable
  let thingToRender = null; //null element will not render
  if(conditionOne){ //based on props or state
    thingToRender = <OptionA />
  } else if(conditionTwo) {
    thingToRender = <OptionB />
  } else if(conditionThree) {
    return null; //show nothing!
  }
    
  //keep return statement as simple as possible!
  return (<div>{thingToRender}</div>);
}

function MyButton(props) {
  //A function that will be called when clicked 
  //The name is conventional, but arbitrary.
  //The callback will be passed the DOM event as usual
  const handleClick = function(event) {
    console.log("clicky clicky");
  }

  //make a button with an `onClick` attribute!
  //this "registers" the listener and sets the callback
  return <button onClick={handleClick}>Click me!</button>;
}

//The current "state"
const state = {
  data: [ {}, {}, {} ],
  ...
}

  
//define presentation - lots of these kinds of functions
function renderData() {
  //render all the data
  //...
}

//define user interaction
button.addEventListener('click', function() {
  //MODIFY THE STATE
  state.data[i] = ...; 

  //CLEAR OLD VIEW AND RE-RENDER CONTENT
  document.querySelector('#main').innerHTML = '';
  renderData(); //RE-RENDER CONTENT    
})

//import the state hook function `useState()` to define state
import React, { useState } from 'react';

function CountingButton(props) {
  const [count, setCount] = useState(0);

  
  
 
  const handleClick = (event) => {
    setCount(count+1); //update the state to be a new value
                       //and RE-RENDER the Component!
  }

  return (
      <button onClick={handleClick}>Clicked {count} times</button>
  );
}

function CountingButton(props) {
  const [count, setCount] = useState(3) //initial value of 3

  const handleClick = (event) => {
    setCount(4); //change `count` to 4 AND re-render!
    console.log(count); //will output "3"; 
                        //state has not changed yet!
  }  
 
  console.log(count); //will have "current" value of state
                      //3 first render, 4 after clicking
  
  return (
    <button onClick={handleClick}>Clicked {count} times</button>
  );    
}

function CountingButton(props) {
  const [count, setCount] = useState(3) //initial value of 3

  console.log("DEBUG: count", count); //debug! variable here, 
                                      //after re-render
  
  
  const handleClick = (event) => {
    setCount(count + 1); //incremenet count AND re-render!
    //do not debug variable here!
  }  
  
  return (
    <button onClick={handleClick}>Clicked {count} times</button>
  );    
}

//Example from React documentation
function ExampleWithManyStates(props) {
  //Declare multiple state variables!
  const [age, setAge] = useState(42);
  const [fruit, setFruit] = useState('banana');
  const [todos, setTodos] = useState([{ text: 'Learn Hooks' }]);
  
  //...  
}

function TodoListWithError(props) {
  //a state value that is an array of objects
  const [todos, setTodos] = useState([{ text: 'Learn Hooks' }]);

  const handleClick = (event) => {
    todos[0].text = "Fix bugs"; //modify the object 
                                //but don't make a new one
    setTodos(todos) //This won't work! Not "changing"
  }
  
  //...
}