jQuery backward selection

I have a form and i'm using this to select it's r开发者_如何学编程adio buttons:

$('form[id^="form-"]').find("input:radio");

But when I use a function on it I have to use this (so that i'll know from which form the function is fired) and this gives me form > radio-button. How can I use this to get the ID of the form?

The simplest and most efficient way is to access the form property of the element in question:

alert(this.form.id);

To traverse from the input to its containing form and get the id, you would use:

$(this).closest('form[id^="form-"]').attr("id");

http://api.jquery.com/category/traversing/

If this is a child element just do:

var form_id = $(this).parent().get(0).id;
//or
var form_id = $(this).parent().attr('id');

$(this).parent().attr('id');

parents() is because I don't know if the inputs are direct descendants of form.