jquery code to determine whether a single check box is selected_jquery

I have read
a Use DOM method to determine whether it is selected

Copy code The code is as follows:

$(function(){
var $cr = $(" #cr");
var cr =$cr[0];
$cr.click(function(){
if(cr.checked){
alert("Thank you for registering");
}
else{
alert("NO");
}
});
});