Javascript >> Google Script array concat doesn't work

Javascript >> Google Script array concat doesn't work from javascript by Clear Civet on Mar 11 2020
const array1 = ['a', 'b', 'c'];
const array2 = ['d', 'e', 'f'];
const array3 = array1.concat(array2);

console.log(array3);
// expected output: Array ["a", "b", "c", "d", "e", "f"]
// console.log and Logger.log do not show array structure. Use JSON.stringify to see correctly.
Logger.log(JSON.stringify(array3));  // expected output: Array ["a", "b", "c", "d", "e", "f"]