전개구문 Spread syntax : 배열
전개구문 Spread syntax : 배열 let arr1 =[1,2,3]; let arr2 =[4,5,6]; let result =[...arr1, ...arr2]; console.log(result); 전개구문 : 객체 let user ={name: 'Mike'} let mike={...user, age:30} console.log(mike) //{name:"Mike", age:30} 전개구문 : 복제 let arr=[1,2,3]; let arr2=[...arr]; //[1,2,3] let user ={name : 'mike', age:30}; let user2={...user}; user2.name="tom"; console.log(user.name); //"mike" console.log(user..
2022. 2. 24.
배열 합치기 reduce
/************************ arr.reduce() /****************************** //배열의 모든 수 합치기 //for, for of, forEach let arr=[1,2,3,4,5,6,7]; let result =0; arr.forEach((num) => { result +=num; }); console.log(result); //출력 ; 28 //************************8 arr.reduce() 인수로 함수를 받는다 (누적 계산값, 현재값) => {return 계산값} ; /****************************** let arr=[1,2,3,4,5,6,7]; const result = arr.reduce((prev,cur..
2022. 2. 20.