动态绘制上拉框

动态绘制下拉框
//需要保留的option
document.getElementById("下拉框的ID").length=1;
//创建option并赋值
var newOption = document.createElement("option");
newOption.value = "对应的value";
newOption.text = "显示的值";
document.getElementById("下拉框的ID").options.add(newOption);