Here's a couple of searches I'd made - 'javascript checkbox value checked then add class to parent' , 'jquery onload' and 'jquery check an object with no action'
The code that worked for me is as such
$("input[type=checkbox], input[type=radio]").each(function(){
console.log('loading checkbox object');
// is(':checked')
if($(this).is(':checked')){
$(this).parent().addClass("chked");
$(this).parent().parent().addClass("chked");
}
});