JavaScript 中 null 是一个对象吗？
可能的重复：
javascript 中的空对象
嗨，我已阅读这个线程关于JavaScript中的null，但我现在对null的身份感到非常困惑。
众所周知，由于 语言设计错误，ECMA 指出 null 是空类型。
8.2 The Null Type
The Null type has exactly one value, called null.
那么为什么人们一直说 null 是一个对象呢？
有人说 null 是单例对象。大家也是这样看待 JavaScript 中的 null 的吗？
Possible Duplicate:
Null object in javascript
Hi, I've read this thread about null in JavaScript, but I'm very confused about the identity of null now.
As it is known that typeof(null) evaluates to object because of the language design error, and ECMA states that null is The Null Type.
8.2 The Null Type
The Null type has exactly one value, called null.
So why people keep saying that null is an object?
Someone said null is a singleton object. Is that how everybody sees the null as in JavaScript too?
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Null 是指不存在对象。 Undefined 表示还没有被赋值，null 表示已经被赋值为空。
Null 并不是真正的单例对象，因为取消引用它会导致错误；
for (var x in null)会给你一个错误。回想一下指针时代； null 是指针未指向对象时所具有的值。Null is the absence of an object. Undefined means it hasn't been assigned yet, and null means it has been assigned to be nothing.
Null is not really a singleton object, because dereferencing it will cause an error;
for (var x in null)will give you an error. Think back to the pointer days; null was the value a pointer had when it was not pointing to an object.不，null 是少数基本类型之一（其他类型包括数字、字符串、布尔值和未定义类型）。其他一切都是对象，包括函数、数组和正则表达式。数字、字符串和布尔值通常被称为“类对象”，因为它们有方法，但它们是不可变的。
另一方面，对象是可变的。No, null is one of the few primitive types (others being numbers, strings, booleans, and undefined). Everything else is an object, including functions, arrays and regular expressions. Numbers, strings and booleans are often called "object-like", because they have methods, but they are immutable.
Objects on the other hand are mutable.null不能被视为对象，因为它没有属性。它是表示原语的关键字，例如true和false。nullcan't be considered an object because it cannot have properties. It is a keyword representing a primitive, liketrueandfalse.