radio JS验证

function checked(){
			var isJumping = true;
			var iskeying = false;
			var field_name = document.getElementsByName("field_name");
			var is_key = document.getElementsByName("is_key");
			for(var i = 0; i < field_name.length; i ++){
				if(field_name[i].value == ""){
					alert("字段名不能为空")
					isJumping = false;
					break;
				}
			}
			for(var i = 0; i < is_key.length; i ++){
				if(is_key[i].checked){
					iskeying=true;
				}
			}
			if(iskeying==false){
				alert("请选择是否主键");
				return iskeying;
			}
			return isJumping;
			
		}