Check all other checkboxes when one is checked

Question

I have a form and group of checkboxes in it. (These checkboxes are dynamically created but I dont think it is important for this question). The code that generates them look

Answer 1

demo

updated_demo

HTML:

 Select all



    checkbox1

    checkbox2

    checkbox3

    checkbox4

JS:

$('.selectall').click(function() {
    if ($(this).is(':checked')) {
        $('div input').attr('checked', true);
    } else {
        $('div input').attr('checked', false);
    }
});