[Javascript] 배열 합치는 방법 5가지(concat, spread, push, Array.from, reduce)

1. concat() 메서드

 

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const combined = arr1.concat(arr2);
console.log(combined); // [1, 2, 3, 4, 5, 6]

 

2. Spread 연산자 

 

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const combined = [...arr1, ...arr2];
console.log(combined); // [1, 2, 3, 4, 5, 6]

 

3. push() 메서드 

 

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
for (let i = 0; i < arr2.length; i++) {
  arr1.push(arr2[i]);
}
console.log(arr1); // [1, 2, 3, 4, 5, 6]

 

4. Array.from() 메서드

 

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const combined = Array.from(arr1).concat(arr2);
console.log(combined); // [1, 2, 3, 4, 5, 6]

 

5. reduce() 메서드

 

const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const combined = arr2.reduce((result, item) => {
  result.push(item);
  return result;
}, arr1);
console.log(combined); // [1, 2, 3, 4, 5, 6]