返回可迭代对象

一般用于对象,普通对象不方便直接遍历，可以转换成数组再遍历

eg:let fruits = ["Banana", "Orange", "Apple", "Mango"];

1.返回对象[key,value]的二维数组

方式一:[...fruits.entries()]

方式二:Object.entries(fruits)

// >[
[0, "Banana"],
[1, "Orange"],
[2, "Apple"],
[3, "Mango"]
]

2.返回对象的 key 数组

Object.keys(fruits) // >['0','1','2','3']

3.返回对象的 values 数组

Object.values(fruits) // >["Banana","Orange","Apple","Mango"]