Using es6 spread to concat multiple arrays

Question

We all know you can do:

let arr1 = [1,2,3];
let arr2 = [3,4,5];
let arr3 = [...arr1, ...arr2]; // [1,2,3,3,4,5]

But how do you make this dynami

Answer 1

You can use spread element within for..of loop to concatenate array values to a single array

let arr1 = [1,2,3];
let arr2 = [3,4,5];
let arr3 = [];

for (let arr of [arr1, arr2 /* , arrN */]) arr3.push(...arr);

console.log(arr3);