[javascript] How to get the containing form of an input?

I need to get a reference to the FORM parent of an INPUT when I only have a reference to that INPUT. Is this possible with JavaScript? Use jQuery if you like.

function doSomething(element) {
    //element is input object
    //how to get reference to form?
}

This doesn't work:

var form = $(element).parents('form:first');

alert($(form).attr("name"));

function doSomething(element) {
  var form = element.form;
}

and in the html, you need to find that element, and add the attribut "form" to connect to that form, please refer to http://www.w3schools.com/tags/att_input_form.asp but this form attr doesn't support IE, for ie, you need to pass form id directly.

Using jQuery:

function doSomething(element) {
    var form = $(element).closest("form").get().
    //do something with the form.
}

Every input has a form property which points to the form the input belongs to, so simply:

function doSomething(element) {
  var form = element.form;
}

simply as:

alert( $(this.form).attr('name') );

I needed to use element.attr('form') instead of element.form.

I use Firefox on Fedora 12.

If using jQuery and have a handle to any form element, you need to get(0) the element before using .form

var my_form = $('input[name=first_name]').get(0).form;

I use a bit of jQuery and old style javascript - less code

$($(this)[0].form) 

This is a complete reference to the form containing the element

And one more....

var _e = $(e.target); // e being the event triggered
var element = _e.parent(); // the element the event was triggered on
console.log("_E " + element.context); // [object HTMLInputElement]
console.log("_E FORM " + element.context.form); // [object HTMLFormElement]
console.log("_E FORM " + element.context.form.id); // form id

would this work? (leaving action blank submits form back to itself too, right?)

<form action="">
<select name="memberid" onchange="this.form.submit();">
<option value="1">member 1</option>
<option value="2">member 2</option>
</select>

"this" would be the select element, .form would be its parent form. Right?

This example of a Javascript function is called by an event listener to identify the form

function submitUpdate(event) {
    trigger_field = document.getElementById(event.target.id);
    trigger_form = trigger_field.form;