import React from 'react';
const Hello = () => {
return (
<div>
<h1 style = {
{
color : 'red',
backgroundColor : 'black'
}
}
>Hello</h1>
</div>
);
};
export default Hello;
.box{
width: 100px;
height: 200px;
background-color: green;
}
import React from 'react';
import './Hello.css';
const Hello = () => {
return (
<div>
<div className='box'></div>
</div>
);
};
export default Hello;
문법 : {모듈명}.module.css
import 방법 : import styles from "./모듈명.module.css";
적용 방법 : {styles.클래스명}
.box{
width: 200px;
height: 50px;
background-color: blue;
}
import React from 'react';
import './Hello.css';
import styles from './Hello.module.css'
const Hello = () => {
return (
<div>
<h1 style = {
{
color : 'red',
backgroundColor : 'black'
}
}
>Hello</h1>
<div className='box'></div>
<div className={styles.box}>Hello</div>
</div>
);
};
export default Hello;
import React from 'react';
const Hello = () => {
function showName(){
console.log("Mike")
}
function showAge(age){
console.log(age)
}
function showText(txt){
console.log(txt)
}
return (
<div>
<h1>Hello</h1>
<button onClick={showName}>Show name</button>
<button onClick ={()=>{
showAge(30)
}}>Show age</button>
<input type = 'text' onChange={(e)=>{
const txt = e.target.value;
showText(txt);
}}></input>
</div>
);
};
export default Hello;
import React, { useState } from 'react';
const Hello = () => {
//let name = 'Mike'
const [name, setName] = useState('Mike');
function changeName(){
const newName = name === 'Mike' ? 'Jane' : 'Mike';
//name이 Mike이면 Jane을 name으로 변경하고, Jane이면
//다시 Mike로 변경
console.log(name);
setName(newName)
}
return (
<div>
<h1>state</h1>
<h2>{name}</h2>
<button onClick={changeName}>Change</button>
</div>
);
};
export default Hello;
const [name, setName] = useState('Mike');
name === 'Mike' ? 'Jane' : 'Mike'
props는 부모 컴포넌트가 자식 컴포넌트에 값을 전달할 때 사용하는 것이다.
import './App.css';
import Hello from './component/Hello';
function App() {
return (
<div className="App">
<Hello age = {10}/>
<Hello age = {20}/>
<Hello age = {30}/>
</div>
);
}
export default App;
import React, { useState } from 'react';
const Hello = (props) => {
console.log(props);
//props.age = 100; -> props 값 변경 불가능
//let name = 'Mike'
const [name, setName] = useState('Mike');
const [age, setAge] = useState(props.age);
function changeName(){
const newName = name === 'Mike' ? 'Jane' : 'Mike';
//name이 Mike이면 Jane을 name으로 변경하고, Jane이면 다시 Mike로 변경
console.log(name);
setName(newName);
setAge(age+1);
}
return (
<div>
<h1>state</h1>
<h2>{name}({age})</h2>
<button onClick={changeName}>Change</button>
</div>
);
};
export default Hello;
import React, { useState } from 'react';
import UserName from './UserName';
const Hello = ({age}) => {
const [name, setName] = useState('Mike');
const msg = age > 19 ? '성인입니다.' : '미성년자입니다.';
return (
<div>
<h2 id = 'name'>
{name}({age}) : {msg}
</h2>
<UserName name={name} />
<button onClick = {()=>{
setName(name === 'Mike'?'Jane':'Mike');
}}>Change</button>
</div>
);
};
export default Hello;