js javascript加载类似星座、血型的函数

 //加载血型
        function bloodtypelaod(constellation) {
            var obj = document.getElementById(‘bloodtype‘);
            obj.options.length = 0;
            var option = document.createElement("option");
            option.value = "0";
            option.text = "请选择";
            obj.add(option);

            var arr = new Array("A型", "B型", "AB型", "O型");
            for (var i = 0; i < arr.length; i++) {
                option = document.createElement("option");
                option.value = i + 1;
                option.text = arr[i];
                if (constellation == arr[i]) {
                    option.selected = true;
                }
                obj.add(option);
            }
        }