how to check available radio button in jquery code example

Example 1: How can I know which radio button is selected via jQuery

if ($('input[name="radioName"]:checked', '#myForm').length) {
	//Yes, it's checked!
}

Example 2: jquery chek radio

//<input type="radio" name="book_condition" value="3" >
$("input:radio[value='3'][name='book_condition']").prop('checked',true);