依年齡排序使用者
重要性：5
撰寫函式 sortByAge(users)，它會取得一個物件陣列，其中包含 age 屬性，並依 age 排序。
例如
let john = { name: "John", age: 25 };
let pete = { name: "Pete", age: 30 };
let mary = { name: "Mary", age: 28 };
let arr = [ pete, john, mary ];
sortByAge(arr);
// now: [john, mary, pete]
alert(arr[0].name); // John
alert(arr[1].name); // Mary
alert(arr[2].name); // Petefunction sortByAge(arr) {
arr.sort((a, b) => a.age - b.age);
}
let john = { name: "John", age: 25 };
let pete = { name: "Pete", age: 30 };
let mary = { name: "Mary", age: 28 };
let arr = [ pete, john, mary ];
sortByAge(arr);
// now sorted is: [john, mary, pete]
alert(arr[0].name); // John
alert(arr[1].name); // Mary
alert(arr[2].name); // Pete