Answers for "jquery mark a checkbox as checked"

jquery set checkbox checked

//jQuery 1.6+ use
$('.checkbox').prop('checked', true);
//jQuery 1.5.x and below use
$('.checkbox').attr('checked', true);

How to check whether a checkbox is checked in jQuery?

//using plane javascript 
if(document.getElementById('on_or_off_checkbox').checked) {
    //I am checked
} 

//using jQuery
if($('#on_or_off_checkbox').is(':checked')){
    //I am checked
}

set checkbox checked jquery

$("#checkboxid").prop('checked', true);  // Checks the box
$("#checkboxid").prop('checked', false); // Unchecks the box

checkbox is checked jquery

$("#out_of_stock_toggle").click(function(){
      if($(this).is(':checked')){
        //show oos
        $(".oos").fadeIn();
      }else{
        //hide oos
        $(".oos").fadeOut();
      }
    });