2021. 1. 15. 17:47ㆍ포트폴리오/React
const { useState,useEffect } = React
const App = (props) => {
const [memdb, setMemdb] = useState([
{
url: 'first',
arr: [
{ url: 'first_1', arr: [] },
{ url: 'first_2', arr: [] }
]
},
{
url: 'second',
arr: [
{ url: 'second_1', arr: [] },
{ url: 'second_2', arr: [] }
]
}
]);
var ch = { url: "test", arr: [{inarr:"in"}] };
useEffect(() => {
console.log(memdb);
setMemdb(memdb=>memdb.map((item,idx)=>{
return idx==1?
{...item, arr: item.arr.map((item_,idx_)=>{
return idx_==0?ch:item_
})}
:
item
}))
}, []);
useEffect(() => {
console.log("changed memdb",memdb);
}, [memdb]);
return (
<>
<h1>text</h1>
</>
);
}
try {
const rootElement = document.getElementById('root')
ReactDOM.render(<App />, rootElement)
} catch (e) { }
* ()=>{ } 화살표 함수 중괄호 이용 시 return 필수