How to focus a form input field when page loaded

In my rails 3 application, I have a view haml file with a form like following:

= form_for(:car, :url => cars_path) do开发者_StackOverflow |f|
  %p
    = f.label :carname
  %p  
    = f.text_field :carname /focus here
  %p
    = f.label :carnr
  %p
    = f.text_field :carnr
  %p
    = f.submit

I would like the input field = f.text_field :carname is in focus when the page is loaded.

How to do it? Is it necessary to use jquery? or is there any Rails way to do the focus?

---

it isn't necessary to use jquery, but it is necessary to use javascript if you're not using HTML5 but you will have to do with jquery or javascript for now:

document.getElementById('carname').focus();

or

$("carname").focus();

with HTML5

= f.text_field :carname, :autofocus => true

There is one caveat on the HTML5 approach: the field that you autofocus does NOT get a focus() event so any CSS styling that you do through onfocus doesn't happen.

---

Use autofocus.

NOTE: HTML5 Only. See browser support.

= form_for(:car, :url => cars_path) do |f|
  %p
   = f.label :carname
 %p  
   = f.text_field :carname, autofocus: true
 %p
   = f.label :carnr
%p
  = f.text_field :carnr
%p
= f.submit