如何强制JQuery发出HTTP 1.0请求并关闭连接

Question

I'm new to jQuery and would like to make a POST request using plain HTTP 1.0 with connection close, instead of the HTTP 1.1 connections that is currently kept alive.

Below is an is the onClick handler for the button that does the post.

$( "#certGenBtn" ).click( function( event ) {
$.ajax({
  type: "POST",
  url: "http://localhost:9099/",
  data: { testVal : "data" },
  success: function( data ) {
              alert( "whoops" );
           },
  beforeSend: function( xhr ) {
                  xhr.setRequestHeader( "Connection", "close" );
              }
    });
});

The raw output dumped on the server side is the following:

POST / HTTP/1.1
Host: localhost:9099
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:21.0) Gecko/20100101 Firefox/21.0
Accept: */*
Accept-Language: en-ZA,en-GB;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Referer: http://localhost/  
Content-Length: 12
Origin: http://localhost
Connection: keep-alive
Pragma: no-cache
Cache-Control: no-cache

testVal=data

The Connection close header is being 'ignored' and the connection remains open to the server so the very last line testVal=data only gets through once i reload the page (I assume this is because the connection is then closed by the browser). I assume it's something very simple and/or stupid that I'm missing but cannot see anything in the documentation.

Answer 1

1) According to the HTTP 1.1 spec, Connection: close is a valid header:

http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html

How about trying to add it with the headers key instead of beforeSend?

.ajax({

   ....
   headers: {Connection: close},

});

2) The jquery docs specify the following function signature for the beforeSend function:

beforeSend 
Type: Function( jqXHR jqXHR, PlainObject settings )

So you might also try adding the header to the settings object rather than the jqXHR object.

Well, I tested your original code as well as my suggestions, and none of them succeed. It looks like the XMLHttpRequest spec forbids setting the Connection header:

The setRequestHeader(header, value) method must run these steps:

Terminate these steps if header is a case-insensitive match for one of the following headers:

... Connection ...

The above headers are controlled by the user agent to let it control those aspects of transport. This guarantees data integrity to some extent.
http://www.w3.org/TR/XMLHttpRequest/#the-setrequestheader-method

Answer 2

var xhr = $.ajax({
    type: "POST",
    url: "some.php",
    data: "name=John&location=Boston",
    success: function(msg){
       alert( "Data Saved: " + msg );
    }
});

//kill the request
xhr.abort()