Answers for "jquery is radio or checkboxchecked"

jQuery check a radio button

// jQuery version 1.6 or above use:  
$("#myRadioID").prop("checked", true);
 
//jQuery versions below 1.6 use:
$("#myRadioID").attr('checked', 'checked');

jquery checkbox

if($("#isAgeSelected").is(':checked'))
    $("#txtAge").show();  // checked
else
    $("#txtAge").hide();  // unchecked