Skip to main content

Submitting Form using FormData object in HTML5 using XmlHttpRequest Level 2

The other day I had posted on uploading a file using XmlHttpRequest 2 and tracking the progress of the file upload process using the progress event on XHR2 object and the progress tag. Another enhancement added to the XHR2 specification is the introduction of FormData object. Using the FormData object, one can create a set of key-value pairs and send them as form data in a XHR request. The FormData object is passed in the send() method of the XHR object:

 var formObject = new FormData();  
 var xhrObject = new XMLHttpRequest();"POST","postform.cfm");  
This means that, one need not add the form element to the document and can avoid using hidden input element (type="hidden") to send the additional key-value data to the server for processing.

It is also possible to add additional data to an already existing form in the document and send the form data to the server: 

 var docFormElement = document.getElementById('myForm');  
 var docFormData = new FormData(docFormElement);  
 var xhrObject = new XMLHttpRequest();"POST","postform.cfm");  

 <form id="myForm">  
   <input name="product_name" type="text" value="ColdFusion" />  
   <input name="product_codename" type="text" value="Zeus" />  

The FormData constructor takes the form element as an argument and then the append function is used to add another key-value data to the FormData object.


  1. HTML5 is widely used by web developers because of it's browser support, mobile capability and especially for game development. Thanks.

  2. cool tutorial ! ,anyway could u give me example how to remove item from docFormData ? thank in advance ^^

  3. There is only one method 'append' available on the FormData object. I think delete and update were not included in the FormData object because of security reasons. If the same was provided then the script could manipulate the original data and could result in security issues.

  4. Hi sagar
    Could you please elaborate on how can I access the docFormData values in doPost() of a simple java class


  5. I think you should also read this little article about spyware applications. They allow users to spy on targets phone and on all messages that are going in/out
    And its easy to use

  6. Read Also
    Track any Person Mobile Number anywhare by Mobile number or CNIC Download This Amazing App Instant Person Tracker

  7. nice and good work now this is amazing and fantastic now
    driveragent plus product key


Post a Comment

Popular posts from this blog

Custom validation messages for HTML5 Input elements using the constraint validation API

HTML5 has introduced several input types such as EMAIL, URL, RANGE, SEARCH, DATE, TIME, etc,. Most of the modern browsers have implemented them and are ready to be used in a HTML document. Another exciting feature introduced in HTML5 is the form validation. Instead of writing JavaScript to validate users input, browsers can now validate it and show an appropriate message if the validation fails. The validation message is shown in line with the field for which the validation has failed. The default error message is shown when the validation fails. In this post I'll explain how these error messages can be changed.

Adding beforeRender and afterRender functions to a Backbone View

I was working on a Backbone application that updated the DOM when a response was received from the server. In a Backbone View, the initialize method would perform some operations and then call the render method to update the view. This worked fine, however there was scenario where in I wanted to perform some tasks before and after rendering the view. This can be considered as firing an event before and after the function had completed its execution. I found a very simple way to do this with Underscore's wrap method.

De-obfuscating javascript code in Chrome Developer Tools

I had blogged about JavaScript debugging with Chrome Developer Tools some time back, wherein I have explained how these developer tools can help in debugging javascript code. Today Google Chrome 12 was released and my Chrome browser was updated to this version. As with every release, there have been some improvements made on performance, usability etc,. One feature that stood out for me is the ability to De-obfuscate the javascript code.

What is Minification?

Minification is the process of removing unnecessary characters such as white spaces, comments, new lines from the source code. These otherwise would be added to make the code more readable. Minifying the source code helps in reducing the file size and thereby reducing the time taken to download the file. This is the reason why most of the popular javascript libraries such as jQuery are minified. A minified jQuery file is of 31 KB in size where as an uncompressed one is about 229 KB. Unfortunately, debugging minified javascript file…