//using plane javascript
if(document.getElementById('on_or_off_checkbox').checked) {
//I am checked
}
//using jQuery
if($('#on_or_off_checkbox').is(':checked')){
//I am checked
}if (!$("#checkboxID").is(":checked")) {
// do something if the checkbox is NOT checked
}// Check a checkbox
$(selector).prop('checked', true);
// Un-check a checkbox
$(selector).prop('checked', false);
// Determine if checked or not
isChecked = $(selector).prop('checked');if ($('[name="your_input_checkbox_name"]').is(":checked"))
{
// it is checked
} else {
// it isn't checked
}if ($('#grepperRocks').is(':checked')) {
// this checkbox is checked
}if($('#checkboxID').is(':checked')){ return true; }