javascript中的解构赋值

// we have an array with the name and surname
let arr = ["John", "Smith"]
// destructuring assignment
// sets firstName = arr[0]
// and surname = arr[1]
let [firstName, surname] = arr;
alert(firstName); // John
alert(surname);  // Smith

let [a, b, c] = "abc"; // ["a", "b", "c"]
let [one, two, three] = new Set([1, 2, 3]);

let options = {
  title: "Menu",
  width: 100,
  height: 200
};
let {title, width, height} = options;
alert(title);  // Menu
alert(width);  // 100
alert(height); // 200