如何用代码块功能插入代码？

Question

问题遇到的现象和发生背景

用代码块功能插入代码，请勿粘贴截图

我想要达到的结果

Answer 1

循环写在方法里面


<script>
        function fillcity() {
            var province = document.getElementById("province").value;
            var cities = null
            console.log("===>", province)
            switch (province) {
                case "四川":
                    cities = ["成都", "内江", "绵阳", "南充"];
                    break;
                case "云南":
                    cities = ["昆明", "大理", "丽江", "楚雄"];
                    break;
                case "湖南":
                    cities = ["秦州", "岳麓", "安定", "长沙"];
                    break;
                case "江苏":
                    cities = ["苏州", "南京", "扬州", "镇江"];
                    break;
            }
            for (var i = 0; i < cities.length; i++) {
                var city = document.getElementById("city");
                city.options[i] = new Option(cities[i], cities[i]);
            }
        }
    </script>