const list = [{ title: "Red" }, { title: "Blue" }, { title: "Yellow" }];

const addColor = (title, array) => array.concat({ title });

​

console.log(addColor("Glam Green", list).length); // 4

console.log(list.length); // 3

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"]

​