Check if inputs are empty using jQuery

Question

I have a form that I would like all fields to be filled in. If a field is clicked into and then not filled out, I would like to display a red background.

Here is my

Answer 1

There is one other thing you might want to think about, Currently it can only add the warning class if it is empty, how about removing the class again when the form is not empty anymore.

like this:

$('#apply-form input').blur(function()
{
    if( !$(this).val() ) {
          $(this).parents('p').addClass('warning');
    } else if ($(this).val()) {
          $(this).parents('p').removeClass('warning');
    }
});