// 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(
    `
${todos.map((todo) => `
${todo}
`).join("")}
`
  );
}
toDoList("wake up", "eat breakfast", ...list); //ul containing: wake up eat breakfast a b c