js spread parameters

                                    obj = {first_name : "Marty",
    lovers: ["Jennifer Parker","Baines McFly"]
      };
let objClone = { ...obj }; // pass all key:value pairs from an object 

console.log(objClone)
// { first_name: "Marty", lovers: ["Jennifer Parker", "Baines McFly"] }

                                    let arr1 = ['A', 'B', 'C'];

let arr2 = ['X', 'Y', 'Z'];

let result = [...arr1, ...arr2];

console.log(result); // ['A', 'B', 'C', 'X', 'Y', 'Z']
// spread elements of the array instead of taking the array as a whole

                                    // seperate each element of array using ...
let list = ['a','b','c'];
let copy = [...list, 'd', 'e']; // ['a', 'b', 'c', 'd', 'e']
//use for infinite parameters to a function
function toDoList(...todos) {
  //todos is an array, so it has map function
  document.write(
    `<ul>${todos.map((todo) => `<li>${todo}</li>`).join("")}</ul>`
  );
}
toDoList("wake up", "eat breakfast", ...list); //ul containing: wake up eat breakfast a b c