JS中length、size区别

length:

let arr = [1,2,3]
console.log(arr.length);   //   数组的长度为3

size()：

let s = [1,2,3,4]
let arr = new Set(s)
console.log(arr);       // Set(4) { 1, 2, 3, 4 }
console.log(arr.size);  //对象的长度为4