hi all: I come across a bug: <html> <head><title>ttt</title> <script src="/jquery.js"></script> <script> $.ajax({ type: 'POST', url: './', beforeSend: function(xhr){
xhr.setRequestHeader('Content-type','application/x-www-form-urlencoded;charset=utf-8'); }, data: { a: 123 } }); </script> </head> <body> </body> </html> the code above in IE will results in the following header: Content-Type application/x-www-form-urlencoded, application/x-www-form-urlencoded;charset=utf-8 I've test with jQuery 1.2.1 and 1.3.2. the error happened when `type' is 'POST', but not 'GET'. I check the source code, and find the following code: 3521 // Set the correct header, if data is being sent 3522 if ( s.data ) 3523 xhr.setRequestHeader("Content-Type", s.contentType); when `type' is 'POST', the s.data is not null, and the `setRequestHeader' is called. and if setRequestHeader is called twice in IE, the latter one will be appended after the former. sorry for my poor English, I hope I've expressed the situation.