JavaScript中的null和undefined,感覺有點易混淆!把Ecma-262下載下來看了看!摘要如下:
Undefined Value
The undefined value is a primitive value used when a variable has not been assigned a value.
4.3.10 Undefined Type
The type Undefined has exactly one value, called undefined.
4.3.11 Null Value
The null value is a primitive value that represents the null, empty, or non-existent reference.
4.3.12 Null Type
The type Null has exactly one value, called null.
感興趣的可以看看如下文章:
http://www.aygfsteel.com/hulizhong/archive/2009/10/22/299430.html