Array：length

const clothing = ["shoes", "shirts", "socks", "sweaters"];

console.log(clothing.length);
// Expected output: 4

const listA = [1, 2, 3];
const listB = new Array(6);

console.log(listA.length);
// 3

console.log(listB.length);
// 6

listB.length = 2 ** 32; // 4294967296
// RangeError: Invalid array length

const listC = new Array(-100); // 负数是不允许的
// RangeError: Invalid array length

const arr = [1, 2];
console.log(arr);
// [ 1, 2 ]

arr.length = 5; // 将数组长度设置为 5，而当前为 2。
console.log(arr);
// [ 1, 2, <3 empty items> ]

arr.forEach((element) => console.log(element));
// 1
// 2

const numbers = [1, 2, 3, 4, 5];
const length = numbers.length;
for (let i = 0; i < length; i++) {
  numbers[i] *= 2;
}
// 遍历后的结果 [2, 4, 6, 8, 10]

const numbers = [1, 2, 3, 4, 5];

if (numbers.length > 3) {
  numbers.length = 3;
}

console.log(numbers); // [1, 2, 3]
console.log(numbers.length); // 3
console.log(numbers[3]); // undefined；多余的元素会被删除

const numbers = [];
numbers.length = 3;
console.log(numbers); // [empty x 3]

"use strict";

const numbers = [1, 2, 3, 4, 5];
Object.defineProperty(numbers, "length", { writable: false });
numbers[5] = 6; // TypeError: Cannot assign to read only property 'length' of object '[object Array]'
numbers.push(5); // // TypeError: Cannot assign to read only property 'length' of object '[object Array]'