XMLHTTP AJAX abort(), jQuery abort()

I was looking if there was a way to stop an already running AJAX request, like we can stop an http request using browser stop button. Yes there is a way to stop it using abort() method of the XMLHttpRequest object . More details about this here http://www.quirksmode.org/blog/archives/2005/09/xmlhttp_notes_a_1.html

jQuery JSONP (JSON with padding) – success method not called

Possible reasons for JSONP success method not getting called

• In jQuery.getJSON method check if you are adding the
  callback=? param to your URL
• Check if your server code serving JSONP request is returning proper JSONP response,

  For example sample server JSONP java code and response taken from IBM Developerworks article given below,
  Java code
  
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String jsonData = getDataAsJson(req.getParameter("symbol"));
String output = req.getParameter("callback") + "(" + jsonData + ");";

  resp.setContentType("text/javascript");

  PrintWriter out = resp.getWriter();
out.println(output);
}

  JSONP Response Format
  
jsonp1232617941775({"symbol" : "IBM", "price" : "91.42"});


To get a good understanding of JSONP you can read this IBM Developerworks article http://www.ibm.com/developerworks/library/wa-aj-jsonp1/

what http error code to use for validation error

I was using 500 – Internal Server Error for validation errors, but problem was the application error handler caught this and shows generic error page, which causes validation logic to fail. So instead we can use

Either use code 400 – Bad Request
or code 200 – with the error message

http://stackoverflow.com/questions/362618/proper-use-of-http-status-codes-in-a-validation-server

Handling cookies with java URLConnection

http://www.hccp.org/java-net-cookie-how-to.html

Same way you can set other headers like Content-Type, Accept to the HTTP request using the setRequestProperty method of URLConnection

Firefox addon to build HTTP request

http://stackoverflow.com/questions/725998/are-there-firefox-extension-or-any-other-browser-that-allow-to-send-arbitrary-p

This needs comes up when you cannot test build HTTP GET or POST request requiring special request headers like content type = application/json;

Apache mod_rewrite NE|noescape

I faced an issue where the URL for example /saved/ was getting rewritten to %2Fsaved%2F, which caused the web application to give 404 error because it expects the URL without escaped/encoded characters.

I found this Stack Overflow thread related to this problem which gave the solution,

http://stackoverflow.com/questions/2443115/apache-mod-rewrite-tomcat-encoding-26-and

Add NE flag to prevent escaping –

http://httpd.apache.org/docs/2.2/rewrite/rewrite_flags.html#flag_ne

Web Performance Test Tools

Tsung
Grinder
JMeter
Faban

From my analysis all the above tools are good and offer advanced features.

jQuery AJAX multipart form-data file upload

jQuery Form plugin provides AJAX form upload capabilities . Since XMLHttpRequest does not support upload , the plugin does it neatly using hidden iframe

IE 8 Browser Modes

IE 8 Developer Tools gives a feature called Browser Modes, with which you can check how your web site works and look in IE 7 without having to install IE 7 . More about this feature here Testing in Different Browser and Document Modes

Firefox and IE Memory Profiler

For Firefox, there is this addon more details about the tool here – Memory Profiler. But this addon is not available for Firefox 3.6.3, So if you are planning to use this plugin you have to install Firefox 3.5

For IE, you can use tool called Drip , and documentation about the tool usage and the common causes for memory leaks explained here