react quick tutorial

1// -------// -------// -------
2// index.js
3// -------// -------// -------
4
5const user = {
6  name: "zidane",
7  email: 'huuvi168@gmail.com'
8};
9
10const element = <h1> {user.name} exist email: {user.email} </h1>;
11
12const element2 = 
13  <div  className="heading"> 
14     <h1> {user.name}  </h1>
15     <h1> {user.email} </h1>
16  </div>;
17
18var numbers = [1,2,3,4];
19var doubleNumbers = numbers.map(function(num){
20  return num * 2 + "; ";
21})
22
23var doubleNumberArrowFunction = numbers.map((num)  => num * 3 + "; ");
24
25var element3 = 
26  <div>
27    Double numbers: {doubleNumberArrowFunction}
28  </div>;
29
30ReactDOM.render(
31  element3,
32  // <React.StrictMode>
33  //   <App />
34  // </React.StrictMode>,
35  document.getElementById('root')
36);
37
38// -------// -------// -------
39// ------- index.css ------
40// -------// -------// -------
41.heading {
42  padding: 10px;
43  color: white;
44  background-color: green;
45}

1ReactDOM.render(  
2    <Hello />,   
3    document.getElementById("root")  
4);
5