September 2022
Intermediate to advanced
585 pages
8h 17m
Chinese
Content preview from JavaScript 经典实例：第三版
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170
第
7
章
对象
JavaScript
类型分为两大类。一类是原生类型，例如字符串和数字。另一类是真正的
对象，都衍生自
JavaScript
的
Object
。
JavaScript
原生对象容易识别。原生对象都有构造函数，通常使用
new
关键字实例化。
常用的数据结构，例如数组、
Date
、错误对象、
Map
和
Set
集合，以及正则表达式
RegExp
都是对象。
JavaScript
对象与传统的面向对象编程语言有一些明显的区别。例如，
JavaScript
允
许创建基本类型
Object
的实例，而且可以在运行时附加属性和函数。其实，你可以
任意修改任何对象的成员，完全不用理会类的定义。
本章深入探讨
JavaScript Object
类型的功能和怪异行为，介绍如何使用
Object
类
型的核心功能检查、扩展和复制各种对象。下一章更进一步，学习规范自定义对象
的最佳实践。
7.1
检查对象的类型
7.1.1
问题
有一个神秘的对象，你想知道它的类型。
对象
｜
171
7.1.2
方案
使用
instanceof
运算符。
const
mysteryObject =
new
Date(2021, 2, 1);
if
(mysteryObject
instanceof
Date) {
//
这里的代码将运行，因为
mysteryObject
是一个 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.