Array.concat()
Merge two or more arrays together. Call Array.concat() on the first array, and pass each array to merge with it in as arguments.
It returns a new array. The original arrays are not modified.
let sandwiches1 = ['turkey', 'tuna', 'blt'];
let sandwiches2 = ['chicken', 'pb&j'];
let allSandwiches = sandwiches1.concat(sandwiches2);
// logs ["turkey", "tuna", "blt"]
console.log(sandwiches1);
// logs ["chicken", "pb&j"]
console.log(sandwiches2);
// logs ["turkey", "tuna", "blt", "chicken", "pb&j"]
console.log(allSandwiches);