$(".class").click(function(){
$(this).find(".subclass").css("visibility","visible");
});
$('.your_class_name')
$(this).find('option:selected').attr("name");
<p id="test" class="hello">Hello</p>
<script>
//Hide all html elements "p"
$("p").hide();
//Hide id="Test"
$("#test").hide();
//Hide all class="hello"
$(".hello").hide();
//Hide all "p" with class="hello"
$("p.test").hide();
</script>
$(".className")
$('.class').jquery_function();
document.querySelector('h1');
//basically the $ = document.querySelector()
//below is the equivalent to above
$('h1'); // by element
$('.by-class');
$('#by-id');
$('.classid')