jquery get the number of selected checkbox

A wording:

According to acquire property name 

function mydel(){
			if($("input[name='delno']:checked").size()==0){
				alert('请选择车次');
			}else{
				$("form[name='trainform']").submit();
			}
		}

Written two:

According to id attribute or class attribute acquisition:

function mydel(){
			alert('请确认是否删除!');
			if($("#check_del:checked").size()==0){
				alert('请选择车次!');
			}else{
				$(".trainform").submit();
			}