动态生成下拉列表并选择某一固定值

treatment.add(new Option("----请选择----", ""));
var i = 0;
for (var key in map) {
if (key == treatmenth) {
treatment.add(new Option(map[key], key));
i++;
var bankSelects = treatment.options;
bankSelects[i].selected = true;
} else {
treatment.add(new Option(map[key], key));
i++;
}