Initially set all checkboxes to checked

I have jquery code that has the ability to set all checkboxes to 'checked' state on the click of a 'check all' checkbox. However, I would like to initially, start a html page by already having all checkboxes checked without having to click on that 'check all' checkbox. Please bear in mind, though, that I would like to keep the 'check all' checkbox since it has the ability to uncheck all checkboxes as well.

Here's my jquery code :

$('.chk_boxes').click(function(){
    var chk = $(this).attr('checked')?true:false;
    $('.chk_boxes1').attr('checked',chk);
});