Overview
The jQuery Form Plugin allows you to easily and unobtrusively upgrade HTML forms to use AJAX. The main methods,ajaxForm
and ajaxSubmit
,
gather information from the form element to determine how to manage the submit process. Both of these methods support
numerous options which allows you to have full control over how the data is submitted. Submitting a form
with AJAX doesn't get any easier than this!
Quick Start Guide
<form id="myForm" action="comment.php" method="post">
Name: <input type="text" name="name" />
Comment: <textarea name="comment"></textarea>
<input type="submit" value="Submit Comment" />
</form>
<head>
<script type="text/javascript" src="path/to/jquery.js"></script>
<script type="text/javascript" src="path/to/form.js"></script>
<script type="text/javascript">
// wait for the DOM to be loaded
$(document).ready(function() {
// bind 'myForm' and provide a simple callback function
$('#myForm').ajaxForm(function() {
alert("Thank you for your comment!");
});
});
</script>
</head>
That's it! When this form is submitted the name and comment fields
will be posted to comment.php. If the server returns
a success status then the user will see a "Thank you" message.
Form Plugin API
The Form Plugin API provides several methods that allow you to easily manage form data and form submission.ajaxForm
- Prepares a form to be submitted via AJAX
by adding all of the necessary event listeners. It does not submit the form.
Use
ajaxForm
in your document'sready
function to prepare your form(s) for AJAX submission.ajaxForm
takes zero or one argument. The single argument can be either a callback function or an Options Object.
Chainable: Yes.Example:
$('#myFormId').ajaxForm();
ajaxSubmit
- Immediately submits the form via AJAX. In the most common use case this is invoked in response to the user submitting the form.
ajaxSubmit
takes zero or one argument. The single argument can be either a callback function or an Options Object.
Chainable: Yes.Example:
// attach handler to form's submit event
$('#myFormId').submit(function() {
// submit the form
$(this).ajaxSubmit();
// return false to prevent normal browser submit and page navigation
return false;
}); formSerialize
- Serializes the form into a query string. This method will return a string in the format:
name1=value1&name2=value2
Chainable: No, this method returns a String.Example:
var queryString = $('#myFormId').formSerialize();
// the data could now be submitted using $.get, $.post, $.ajax, etc
$.post('myscript.php', queryString);
fieldSerialize
- Serializes field elements into a query string. This is handy when you need to serialize only
part of a form. This method will return a string in the format:
name1=value1&name2=value2
Chainable: No, this method returns a String.Example:
var queryString = $('#myFormId .specialFields').fieldSerialize();
fieldValue
- Returns the value(s) of the element(s) in the matched set in an array. As of version .91,
this method always returns an array.
If no valid value can be determined the
array will be empty, otherwise it will contain one or more values.
Chainable: No, this method returns an array.Example:
// get the value of the password input
var value = $('#myFormId :password').fieldValue();
alert('The password is: ' + value[0]); resetForm
- Resets the form to its original state by invoking the form element's native
DOM method.
Chainable: Yes.Example:
$('#myFormId').resetForm();
clearForm
- Clears the form elements. This method emptys all of the text inputs, password inputs and textarea elements, clears
the selection in any select elements, and unchecks all radio and checkbox inputs.
Chainable: Yes.$('#myFormId').clearForm();
clearFields
- Clears field elements. This is handy when you need to clear only a part of the form.
Chainable: Yes.$('#myFormId .specialFields').clearFields();
The Options Object
BothajaxForm
and ajaxSubmit
support
numerous options which can be provided using an Options Object. The Options Object is simply
a JavaScript Object that contains properties with values set as follows:
Example:
// prepare Options Object
var options = {
target: '#divToUpdate',
url: 'comment.php',
success: function() {
alert('Thanks for your comment!');
}
};
// pass options to ajaxForm
$('#myForm').ajaxForm(options);
Note that the Options Object can also be used to pass values to jQuery's
$.ajax
method.
If you are familiar with the options supported by $.ajax
you may use them in the Options Object passed to ajaxForm
and
ajaxSubmit
.
Code Samples
The following code controls the HTML form beneath it. It uses ajaxForm
to bind the form and demonstrates how to use pre- and post-submit callbacks.
// prepare the form when the DOM is ready
$(document).ready(function() {
var options = {
target: '#output1', // target element(s) to be updated with server response
beforeSubmit: showRequest, // pre-submit callback
success: showResponse // post-submit callback
// other available options:
//url: url // override for form's 'action' attribute
//type: type // 'get' or 'post', override for form's 'method' attribute
//dataType: null // 'xml', 'script', or 'json' (expected server response type)
//clearForm: true // clear all form fields after successful submit
//resetForm: true // reset the form after successful submit
// $.ajax options can be used here too, for example:
//timeout: 3000
};
// bind form using 'ajaxForm'
$('#myForm1').ajaxForm(options);
});
// pre-submit callback
function showRequest(formData, jqForm, options) {
// formData is an array; here we use $.param to convert it to a string to display it
// but the form plugin does this for you automatically when it submits the data
var queryString = $.param(formData);
// jqForm is a jQuery object encapsulating the form element. To access the
// DOM element for the form do this:
// var formElement = jqForm[0];
alert('About to submit: \n\n' + queryString);
// here we could return false to prevent the form from being submitted;
// returning anything other than false will allow the form submit to continue
return true;
}
// post-submit callback
function showResponse(responseText, statusText) {
// for normal html responses, the first argument to the success callback
// is the XMLHttpRequest object's responseText property
// if the ajaxForm method was passed an Options Object with the dataType
// property set to 'xml' then the first argument to the success callback
// is the XMLHttpRequest object's responseXML property
// if the ajaxForm method was passed an Options Object with the dataType
// property set to 'json' then the first argument to the success callback
// is the json data object returned by the server
alert('status: ' + statusText + '\n\nresponseText: \n' + responseText +
'\n\nThe output div should have already been updated with the responseText.');
}
Output Div (#output1):
The following code controls the HTML form beneath it. It uses ajaxSubmit
to submit the form.
// prepare the form when the DOM is ready
$(document).ready(function() {
var options = {
target: '#output2', // target element(s) to be updated with server response
beforeSubmit: showRequest, // pre-submit callback
success: showResponse // post-submit callback
// other available options:
//url: url // override for form's 'action' attribute
//type: type // 'get' or 'post', override for form's 'method' attribute
//dataType: null // 'xml', 'script', or 'json' (expected server response type)
//clearForm: true // clear all form fields after successful submit
//resetForm: true // reset the form after successful submit
// $.ajax options can be used here too, for example:
//timeout: 3000
};
// bind to the form's submit event
$('#myForm2').submit(function() {
// inside event callbacks 'this' is the DOM element so we first
// wrap it in a jQuery object and then invoke ajaxSubmit
$(this).ajaxSubmit(options);
// !!! Important !!!
// always return false to prevent standard browser submit and page navigation
return false;
});
});
// pre-submit callback
function showRequest(formData, jqForm, options) {
// formData is an array; here we use $.param to convert it to a string to display it
// but the form plugin does this for you automatically when it submits the data
var queryString = $.param(formData);
// jqForm is a jQuery object encapsulating the form element. To access the
// DOM element for the form do this:
// var formElement = jqForm[0];
alert('About to submit: \n\n' + queryString);
// here we could return false to prevent the form from being submitted;
// returning anything other than false will allow the form submit to continue
return true;
}
// post-submit callback
function showResponse(responseText, statusText) {
// for normal html responses, the first argument to the success callback
// is the XMLHttpRequest object's responseText property
// if the ajaxSubmit method was passed an Options Object with the dataType
// property set to 'xml' then the first argument to the success callback
// is the XMLHttpRequest object's responseXML property
// if the ajaxSubmit method was passed an Options Object with the dataType
// property set to 'json' then the first argument to the success callback
// is the json data object returned by the server
alert('status: ' + statusText + '\n\nresponseText: \n' + responseText +
'\n\nThe output div should have already been updated with the responseText.');
}
Output Div (#output2):
This page gives several examples of how form data can be validated before it is sent to
the server. The secret is in the beforeSubmit
option. If this
pre-submit callback returns false, the submit process is aborted.
The following login form is used for each of the examples that follow. Each example will validate that both the username and password fields have been filled in by the user.
Form Markup:
<form id="validationForm" action="dummy.php" method="post">
Username: <input type="text" name="username" />
Password: <input type="password" name="password" />
<input type="submit" value="Submit" />
</form>
First, we initialize the form and give it a beforeSubmit
callback function - this is the validation function.
// prepare the form when the DOM is ready
$(document).ready(function() {
// bind form using ajaxForm
$('#myForm2').ajaxForm( { beforeSubmit: validate } );
});
Validate Using the formData
Argument
function validate(formData, jqForm, options) {
// formData is an array of objects representing the name and value of each field
// that will be sent to the server; it takes the following form:
//
// [
// { name: username, value: valueOfUsernameInput },
// { name: password, value: valueOfPasswordInput }
// ]
//
// To validate, we can examine the contents of this array to see if the
// username and password fields have values. If either value evaluates
// to false then we return false from this method.
for (var i=0; i < formData.length; i++) {
if (!formData[i].value) {
alert('Please enter a value for both Username and Password');
return false;
}
}
alert('Both fields contain values.');
}
Validate Using the jqForm
Argument
function validate(formData, jqForm, options) {
// jqForm is a jQuery object which wraps the form DOM element
//
// To validate, we can access the DOM elements directly and return true
// only if the values of both the username and password fields evaluate
// to true
var form = jqForm[0];
if (!form.username.value || !form.password.value) {
alert('Please enter a value for both Username and Password');
return false;
}
alert('Both fields contain values.');
}
Validate Using the fieldValue
Method
function validate(formData, jqForm, options) {
// fieldValue is a Form Plugin method that can be invoked to find the
// current value of a field
//
// To validate, we can capture the values of both the username and password
// fields and return true only if both evaluate to true
var usernameValue = $('input[@name=username]').fieldValue();
var passwordValue = $('input[@name=password]').fieldValue();
// usernameValue and passwordValue are arrays but we can do simple
// "not" tests to see if the arrays are empty
if (!usernameValue[0] || !passwordValue[0]) {
alert('Please enter a value for both Username and Password');
return false;
}
alert('Both fields contain values.');
}
Note
You can find jQuery plugins that deal specifically with field validation on the jQuery Plugins Page.This page shows how to handle JSON data returned from the server.
The form below submits a message to the server and the server
echos it back in JSON format.
Form markup:
<form id="jsonForm" action="json-echo.php" method="post">
Message: <input type="text" name="message" value="Hello JSON" />
<input type="submit" value="Echo as JSON" />
</form>
Server code in
json-echo.php
:
<?php echo '{ message: "' . $_POST['message'] . '" }'; ?>
JavaScript:
// prepare the form when the DOM is ready
$(document).ready(function() {
// bind form using ajaxForm
$('#jsonForm').ajaxForm({
// dataType identifies the expected content type of the server response
dataType: 'json',
// success identifies the function to invoke when the server response
// has been received
success: processJson
});
});
Callback function
function processJson(data) {
// 'data' is the json object returned from the server
alert(data.message);
}
This page shows how to handle HTML data returned from the server.
The form below submits a message to the server and the server
echos it back in an HTML div. The response is added to this
page in the htmlExampleTarget
div below.
Form markup:
<form id="htmlForm" action="html-echo.php" method="post">
Message: <input type="text" name="message" value="Hello HTML" />
<input type="submit" value="Echo as HTML" />
</form>
Server code in
html-echo.php
:
<?php
echo '<div style="background-color:#ffa; padding:20px">' . $_POST['message'] . '</div>';
?>
JavaScript:
// prepare the form when the DOM is ready
$(document).ready(function() {
// bind form using ajaxForm
$('#htmlForm').ajaxForm({
// target identifies the element(s) to update with the server response
target: '#htmlExampleTarget',
// success identifies the function to invoke when the server response
// has been received; here we apply a fade-in effect to the new content
success: function() {
$('#htmlExampleTarget').fadeIn('slow');
}
});
});
htmlExampleTarget (output will be added below):
This page shows how to handle XML data returned from the server.
The form below submits a message to the server and the server
echos it back in XML format.
Form markup:
<form id="xmlForm" action="xml-echo.php" method="post">
Message: <input type="text" name="message" value="Hello XML" />
<input type="submit" value="Echo as XML" />
</form>
Server code in
xml-echo.php
:
<?php
// !!! IMPORTANT !!! - the server must set the content type to XML
header('Content-type: text/xml');
echo '<root><message>' . $_POST['message'] . '</message></root>';
?>
JavaScript:
// prepare the form when the DOM is ready
$(document).ready(function() {
// bind form using ajaxForm
$('#xmlForm').ajaxForm({
// dataType identifies the expected content type of the server response
dataType: 'xml',
// success identifies the function to invoke when the server response
// has been received
success: processXml
});
});
Callback function
function processXml(responseXML) {
// 'responseXML' is the XML document returned by the server; we use
// jQuery to extract the content of the message node from the XML doc
var message = $('message', responseXML).text();
alert(message);
}
This page demonstrates the Form Plugin's file upload capabilities. There is no special coding required to handle file uploads. File input elements are automatically detected and processed for you.
Since it is not possible to upload files using the browser's
XMLHttpRequest
object, the Form Plugin uses a hidden iframe element to help with the task. This is a
common technique, but it has inherent limitations. The iframe element is used as the target
of the form's submit operation which means that the server response is written to the iframe.
This is fine if the response type is HTML or XML[1], but doesn't work as well if the response type is
script or JSON, both of which often contain characters that need to be repesented using entity
references when found in HTML markup.
To account for the challenges of script and JSON responses, the Form Plugin allows these responses
to be embedded in a textarea
element and it is recommended that you
do so for these response types when used in conjuction with file uploads. Please note, however,
that if a file has not been selected by the user for the file input then the request uses normal
XHR to submit the form (not an iframe). This puts the burden on your server code to know when
to use a textarea and when not to. If you like, you can use the iframe
option of the plugin to force it to always use an iframe mode and then your server can
always embed the response in a textarea.
The following response shows how a script should be returned from the server:
<textarea>
for (var i=0; i < 10; i++) {
// do some processing
}
</textarea>
The form below provides an input element of type "file" along with a select element
to specify the dataType of the response. The form is submitted to
files.php
which uses the dataType to
determine what type of response to return.
Working With Fields
This page describes and demonstrates the Form Plugin'sfieldValue
and
fieldSerialize
methods.
fieldValue
fieldValue
allows you to retrieve the current value of a field. For example, to retrieve the value of the password
field in a form with the id of 'myForm' you would write:
var pwd = $('#myForm :password').fieldValue()[0];
This method always returns an array. If no valid value can be determined the
array will be empty, otherwise it will contain one or more values.
fieldSerialize
fieldSerialize
allows you to serialize a subset of a form into a
query string. This is useful when you need to process only certain fields. For example,
to serialize only the text inputs of a form you would write:
var queryString = $('#myForm :text').fieldSerialize();
[1] http://www.w3.org/TR/html4/interact/forms.html#successful-controls.
By default, fieldValue
and fieldSerialize
only function on 'successful controls'. This means that if you run the
following code on a checkbox that is not checked, the result will be an
empty array.
// value will be an empty array if checkbox is not checked:
var value = $('#myUncheckedCheckbox').fieldValue();
// value.length == 0
However, if you really want to know the 'value' of the checkbox element, even if it's unchecked, you can
write this:
// value will hold the checkbox value even if it's not checked:
var value = $('#myUncheckedCheckbox').fieldValue(false);
// value.length == 1
Frequently Asked Questions
- What versions of jQuery is the Form Plugin compatible with?
- The Form Plugin is compatible with jQuery v1.0.3 and later.
- Does the Form Plugin have any dependencies on other plugins?
- No.
- Is the Form Plugin fast?
- Yes! See our comparison page for a look at how the Form Plugin compares to other libraries (including Prototype and dojo).
- What is the easiet way to use the Form Plugin?
ajaxForm
provides the simplest way to enable your HTML form to use AJAX. It's the one-stop-shopping method for preparing forms.- What is the difference between
ajaxForm
andajaxSubmit
? - There are two main differences between these methods:
ajaxSubmit
submits the form,ajaxForm
does not. When you invokeajaxSubmit
it immediately serializes the form data and sends it to the server. When you invokeajaxForm
it adds the necessary event listeners to the form so that it can detect when the form is submitted by the user. When this occursajaxSubmit
is called for you.- When using
ajaxForm
the submitted data will include the name and value of the submitting element (or its click coordinates if the submitting element is an image).
- How can I cancel a form submit?
- You can prevent a form from being submitted by adding a 'beforeSubmit' callback function and returning false from that function. See the Code Samples page for an example.
- Is there a unit test suite for the Form Plugin?
- Yes! The Form Plugin has an extensive set of tests that are used to validate its functionality. Run unit tests.
- Does the Form Plugin support file uploads?
- Yes!
Download
The Official Form Plugin is available in the jQuery Subversion repository: http://jqueryjs.googlecode.com/svn/trunk/plugins/form/jquery.form.js.There are many other useful Form Plugins available from the jQuery Plugins page.
Support
Support for the Form Plugin is available through the jQuery Mailing List. This is a very active list to which many jQuery developers and users subscribe.Access to the jQuery Mailing List is also available through the Nabble Forums.
Contributors
Development of the Form Plugin was a community effort with many people contributing ideas and code. The following people have made contributions of one kind or another:- John Resig
- Mike Alsup
- Mark Constable
- Klaus Hartl
- Matt Grimm
- Yehuda Katz
- Jörn Zaefferer
- Sam Collett
- Gilles van den Hoven
- Kevin Glowacz