IE7默认表单方法是“GET”。 如何判断它是用户输入还是默认？

Question

If a user creates a form without a method attribute, it seems like most browsers will handle this at the time of form submission. So upon inspection of the form element after the DOM is ready, you can see that there is no "method" attr of the form element object.

IE7, however, apparently sets a default method value of "GET" on all forms without a method value. I don't want to argue about whether GET or POST is the most sensible default, I just want to find a way to make POST the default form method across all browsers.

My problem is that I can't tell if the user entered a "GET" value for a form method, or if IE injected that value as default. If there is no method attribute of the form, it is obvious that the users didn't specify one, so I can safely default it to POST. But if I see a GET value for a form method, I can't tell if the user specified that, or if it was left black and IE7 set GET when it parsed the HTML.

Anyone have any ideas?

Answer 1

IE's behaviour is correct !(*) According to DTD:

method      (GET|POST)     GET       -- HTTP method used to submit the form--

or, in the XHTML DTD:

method      (get|post)     "get"

that means if the method attribute is omitted, not only does the form submit as GET by default, but the DOM actually should contain an Attr node for method with the DTD defaulted value GET .

(*: well, sort of. IE is using the XHTML lower-case default in an HTML document where it should be the upper-case. Not that it really matters as the attribute is case-insensitive in HTML anyhow. And hey! It's IE getting the standard more-right than all the other browsers. It's a miracle!)

So how do you tell that the Attr node was put there because of DTD attribute defaulting and not because it was in the source? With the DOM Level 1 Core specified flag:

var form= document.getElementById('myform');
var attr= form.getAttributeNode('method');
var isomitted= attr===null || !attr.specified;

Answer 2

This doesn't seem to be in violation of the HTML form spec , which states:

This attribute specifies which HTTP method will be used to submit the form data set. Possible (case-insensitive) values are "get" (the default) and "post". See the section on form submission for usage information

Answer 3

(How do I reply to a specific reply?) (in reply to bobice:)

IE's behaviour is correct!

If I read the relevant specs correctly, these are all the case in conformant implementations (which IE is not):

form.method == "get" /* IETF and W3C HTMLs and XHTMLs */ || form.method == "GET" /* HTML5* */
form.hasAttribute ("method") == false
form.getAttribute ("method") == ""
form.getAttributeNode ("method") == null

In Chrome "8.0.552.28 beta" on Linux, I get (also not correct)

var form = document.createElement ("form")
undefined
form.method == "get" || form.method == "GET"
false /* actual value is "" */
form.hasAttribute ("method") == false
true
form.getAttribute ("method") == ""
false /* actual value is null */
form.getAttributeNode ("method") == null
true

• In HTML5, method is an enumerated attribute equal to one of GET, POST, PUT, DELETE. form.method must "reflect" the method attribute, which in the case of an enumerated attribute means the specified value if it matches one of the valid values or else the first valid value. (I may be reading this slightly wrong, but that is my interpretation.)