html字段长度限制,HTML属性的长度是否有限制？

HTML 4

From an HTML 4 perspective, attributes are an SGML construct. Their limits are defined in the SGML Declaration of HTML 4:

QUANTITY SGMLREF

ATTCNT 60 -- increased --

ATTSPLEN 65536 -- These are the largest values --

LITLEN 65536 -- permitted in the declaration --

NAMELEN 65536 -- Avoid fixed limits in actual --

PILEN 65536 -- implementations of HTML UA's --

TAGLVL 100

TAGLEN 65536

GRPGTCNT 150

GRPCNT 64

The value in question here is "ATTSPLEN" which would be the limit on an element's attribute specification list (which should be the total size of all attributes for that element). The note above mentions that fixed limits should be avoided, however, so it's likely that there is no real limit other than available memory in most implementations.

HTML 5

HTML 5 seems to be different, as the spec says, "This version of HTML thus returns to a non-SGML basis."

Later on, when describing how to parse HTML 5, the following passage appears (emphasis added):

The algorithm described below places

no limit on the depth of the DOM tree

generated, or on the length of tag

names, attribute names, attribute

values, text nodes, etc. While

implementors are encouraged to avoid

arbitrary limits, it is recognized

that practical concerns will likely

force user agents to impose nesting

depth constraints.

So I suppose that is your answer.