getAttribute 

大部分介绍都说只有一个，包括w3cschool！

其实这个方法在iE7下有两个参数！

Syntax

Parameters

strAttributeName [in]

Type: String

String that specifies the name of the attribute.

lFlags [in, optional]

Type: Integer

Integer that specifies one or more of the following flags:

0

Default. Performs a property search that is not case-sensitive, and returns an interpolated value if the property is found.

1

Performs a case-sensitive property search. To find a match, the uppercase and lowercase letters in strAttributeName must exactly match those in the attribute name.

2

Returns attribute value as a String. This flag does not work for event properties.

4

Returns attribute value as a fully expanded URL. Only works for URL attributes.

Return value

Type: Variant

Variant that returns a String, Variant of type Integer, or Boolean value as defined by the attribute. If the attribute is not present, this method returns null.

msdn：http://msdn.microsoft.com/en-us/library/ms536429(VS.85).aspx